KR101331950B1 - Ultra lightweight polymer concrete composition and molded articles using the same - Google Patents

Abstract

The present invention provides ultralight polymer concrete composition, which includes 20-80 weight% of a first resin, 10-30 weight% of a second resin, 2-8 weight% of a silane coating agent, 3-8 weight% of a rigidity enhancer, and 10-25 weight% of an inorganic hollow body, and a molded article obtained by hardening the same.

Description

ULTRA LIGHTWEIGHT POLYMER CONCRETE COMPOSITION AND MOLDED ARTICLES USING THE SAME

The present invention provides a variety of civil and building structures, underwater and offshore structures, nuclear and power plant structures, nuclear waste treatment structures, precast structures, salt-resistant structures, more specifically slabs of high or high-rise buildings, road bridge decks, railway slabs, The present invention relates to a super lightweight polymer concrete composition for use in high elastic rail sleepers, tunnel grouting, interlayer noise absorbing materials, refrigeration and storage warehouse insulation flooring materials, and high thermal insulation PC walls.

Lightweight concrete refers to concrete made for the purpose of reducing the weight of concrete, and generally divided into lightweight aggregate concrete using lightweight aggregate and lightweight foamed concrete containing air bubbles.

General lightweight aggregate concrete refers to concrete using lightweight aggregate in all or part of aggregate. However, lightweight aggregate, the main raw material of lightweight aggregate concrete, relies on expensive imports for the most part due to lack of domestic technology, and high rigidity even if imported raw materials are used due to the low strength of lightweight aggregate itself and the limitation of the strength of existing concrete. There is a problem that is difficult to manufacture lightweight concrete.

As a way to overcome the problems of the light weight aggregate concrete as described above, a lot of research has been carried out to develop a light weight foam concrete light weight by making a lot of bubbles in the concrete without using the fine aggregate. Republic of Korea Patent No. 10-1127771 describes a manufacturing method of structural lightweight concrete to reduce the weight of the concrete by generating a number of bubbles independently while using the general aggregate instead of the lightweight aggregate.

In general, lightweight foamed concrete has the advantage of being able to be used as a structural material, that is, a wall material, a floor material, a roofing material, etc., when the weight per unit volume is more than 10 times lighter than ordinary concrete and reinforced with reinforcing bars. In addition, foamed concrete in which reinforcing bars are not used may be manufactured in a block form and used as a wall material.

Lightweight foamed concrete can be classified into three types: high pressure steam curing (ALC), atmospheric steam curing (PALC), and in-situ casting (for apartment insulation) lightweight concrete. , Pre-foam method, and mix-foam method. These types can be distinguished by mixing the foaming agent in a slurry and foaming, and mixing the foam in a slurry in advance. A method of foaming bubbles in a slurry is a method used in manufacturing a product such as ALC, and uses a metal powder foaming agent (Al powder, Zn powder, etc.).

However, ALC and the like have high economical cost due to high factory construction cost and manufacturing cost.In case of on-the-spot casting, if bubbles are generated separately and mixed with ready-mixed concrete, the troublesome and economical efficiency due to separate installation of bubble generator and mixing facility It matters. In addition, there is a problem such as an increase in cracks and specific gravity due to volume reduction due to the defoaming of bubbles after construction.

Republic of Korea Patent No. 10-1127771 (2012.03.23)

The present invention has been made to solve the conventional problems as described above, the object of the present invention is the pump pump can be the same as the conventional heavy-weight concrete casting, as well as the site casting as well as precast construction possible economical and ease of construction To provide an ultralight polymer concrete composition having excellent compressive strength, flexural strength, tensile strength and adhesion strength.

In addition, another object of the present invention is to provide a molded article obtained by curing the ultralight polymer concrete composition.

Ultra lightweight polymer concrete composition according to the present invention for achieving the above object is 50 to 60% by weight of the first resin, 10 to 30% by weight of the second resin, 2 to 8% by weight of the silane coating agent, 3 to 8% by weight of the strength enhancer and inorganic 10-25 wt% of the hollow body.

In addition, the first resin may be characterized in that it comprises at least one selected from the group consisting of polyurethane and polyurethane acrylate.

In addition, the second resin may be characterized in that it comprises at least one selected from the group consisting of polymethyl methacrylate, methyl methacrylate, alkyd, phenol, unsaturated polyester and polyvinyl alcohol.

In addition, the silane coating agent includes at least one silane compound selected from the group consisting of alkoxy silane, amino silane, epoxy silane, acrylic silane, mercapto silane, fluorine silane, methoxy silane, vinyl silane, chloro silane and silazane. It may be characterized by.

In addition, the strength enhancer may be characterized in that it comprises one or more selected from the group consisting of calcium carbonate, calcium chloride, calcium hydroxide and gypsum.

In addition, the inorganic hollow body is the inorganic hollow body is one selected from the group consisting of vermiculite, diatomaceous earth, kaolin, bentonite, bauxite, ball clay, onyxel, attapulgite, quartz, glass bubble, coreresyl and microporous It may be characterized by including the above.

In addition, the inorganic hollow body may be characterized in that the inorganic hollow body coated with a silane compound.

In addition, the ultra-light polymer concrete composition is characterized in that it further comprises one or more additives selected from the group consisting of impact modifiers, antibacterial agents, mold release agents, heat stabilizers, antioxidants, light stabilizers, colorants, stabilizers, pigments, dyes and opacifiers. can do.

The present invention includes a molded article obtained by curing the ultralight polymer concrete composition.

In addition, the molded article may include a molded article having a specific gravity of 0.5 to 0.8.

The molded article may include a molded article having a compressive strength of 50 to 90 MPa, a flexural strength of 15 to 25 MPa, a tensile strength of 8 to 20 MPa, and an adhesion strength of 5 to 6 MPa.

The ultra-light polymer concrete composition according to the present invention is capable of pumping the same pump as the conventional heavy-weight concrete, so that not only the site casting but also the precast construction can reduce various costs and popularize the structural ultra-light polymer concrete.

In addition, the ultra-light polymer concrete composition according to the present invention has excellent construction quality due to excellent properties such as compressive strength of 50 to 90 MPa, flexural strength of 15 to 25 MPa, tensile strength of 8 to 20 MPa, and adhesion strength of 5 to 6 MPa. Provide convenience and economics at the same time.

Hereinafter, the present invention will be described in more detail.

In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. It is to be understood that the following terms are defined in consideration of the functions of the present invention, and may be changed according to the intention of the user, the operator, or the precedent, and the meaning of each term should be interpreted based on the contents will be.

As described above, the ultralight polymer concrete composition according to the present invention is 50 to 60% by weight of the first resin, 10 to 30% by weight of the second resin, 2 to 8% by weight of the silane coating agent, 3 to 8% by weight of the strength enhancer and inorganic hollow It comprises 10 to 25% by weight of the sieve, and may optionally further comprise an additive.

The ultralight polymer concrete composition according to the present invention may be prepared according to a conventional method for preparing a polymer concrete composition, and may have a form of a dry mixture, a solution, a dispersion, a suspension, a slurry, a paste, a dried or cured product, a multilayered composite, or the like. Can be. In addition, the composition according to the present invention can be molded into various articles, applied on various articles, or incorporated into various articles. The molded article and the like includes all articles manufactured using conventional concrete compositions, and various civil and building structures, underwater and marine structures, nuclear and power plant structures, nuclear waste treatment structures, precast structures, salt prevention structures, and more. Specific examples include, but are not limited to, slabs of high or high rise buildings, road bridge decks, railroad slabs, high elastic rail sleepers, tunnel grouting, interlayer noise materials, refrigeration and storage warehouse insulation floor materials, and high insulation PC walls. Moreover, the method normally used in the said field | area can also be used also for the said shaping | molding method or a coating method.

Hereinafter, each component constituting the ultralight polymer concrete composition according to the present invention will be described in detail.

(1) first resin

The first resin of the ultra-light polymer concrete composition according to the present invention may include at least one selected from the group consisting of polyurethane and polyurethane acrylate as a material that is a main raw material of the ultra-light polymer concrete composition. In general, in contrast to unsaturated polyester-based resin used in lightweight concrete shows a cracking phenomenon, in the case of a urethane-based resin can be prevented due to the elastic force of the urethane. In addition, the first resin is preferably contained in 20 to 80% by weight can express the physical properties required in the present invention, it is more preferably contained in 50 to 60% by weight.

The polyurethane includes all high molecular compounds having a urethane bond made of a combination of an alcohol group and an isocyanic acid group, and includes urethane foam containing bubbles in the polyurethane as well as spandex or urethane-based synthetic rubber made of synthetic fibers. The urethane-based synthetic rubber has a polyester-based and polyether-based, the polyester-based is made of a polyester by reacting propylene glycol and ethylene glycol with adipic acid, naphthalene-1,5- having a molecular weight of 3,000 having a hydroxyl group at both ends It is made of a polymer by urethaneization with diisocyanic acid, and polyether type is made of high molecular weight polyurethane by reacting terminal hydroxy group of polyether mixed with propylene oxide with toluylene diisocyanic acid.

The polyurethane acrylate may be prepared by introducing an acrylate group into the polyurethane, but is not limited thereto. In addition, the polyurethane acrylate includes a polymer of acrylic ester, a copolymer of ethyl acrylate and chloroethyl vinyl ether, a copolymer of ethyl or butyl acrylate and acrylonitrile, and the like. Since the polyurethane acrylate is very excellent in oil resistance and heat resistance even at high temperatures, it exhibits suitable properties as the first resin of the ultralight polymer concrete composition according to the present invention.

In addition, the polyurethane or polyurethane acrylate includes a functional copolymer. The polyurethane or polyurethane acrylate functional copolymer may be formed by copolymerizing a polyurethane or polyurethane acrylate oligomer and a fluorine-based acrylic monomer. In addition, if necessary, the copolymerization may further include one or more monomers capable of radical polymerization, but is not limited thereto. Polyurethane or polyurethane acrylate oligomer with excellent hardness and fluorine acrylate monomer with low surface energy can be prepared by copolymerization using radical solution polymerization method. The resin produced can have a scratch and antifouling property in one copolymer. And adhesion at the same time.

The polyurethane or polyurethane acrylate oligomer may be prepared by a method known in the art or commercially available. After polymerizing a polyol and a diisocyanate compound to obtain an isocyanate terminated polyurethane prepolymer, the isocyanate terminated polyurethane prepolymer is reacted with a vinyl monomer having both a hydroxyl group and an acryl group in the molecule to end capping with an acrylate to obtain a polyurethane acrylate oligomer It can be manufactured. Here, the diisocyanate is not limited, but toluene 2,4-diisocyanate, diphenyl diisocyanate, xylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, tetramethyl xylene diisocyanate, 4,4-dicyclo Hexyl methane diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, diphenylmethane-4,4'- diisocyanate, lysine diisocyanate can be selected have. Examples of the polyol include, but are not limited to, polypropylene glycol, polytetramethylene glycol, polycarbonate, polycaprolactone, polyester, ethylene glycol, propylene glycol, butanediol, 1,6 hexanediol, glycerol, trimethiropropane, pentaerythritol One or more of the may be selected. Examples of vinyl monomers having both a hydroxy group and an acryl group in a molecule include, but are not limited to, at least one of hydroxyethyl acrylate, hydroxymethyl acrylate, hydroxypropyl acrylate, and ε-caprolactone-β-hydroxyethyl acrylate. Can be selected and used.

(2) second resin

The second resin of the ultralight polymer concrete composition according to the present invention may include at least one selected from the group consisting of polymethyl methacrylate, methyl methacrylate, alkyd, phenol, unsaturated polyester and polyvinyl alcohol. In addition, the second resin is preferably contained in 10 to 30% by weight can express the physical properties required in the present invention, it is more preferably included in 15 to 20% by weight.

The polymethyl methacrylate includes acrylic particles crosslinked with polymethyl methacrylate. In addition, the polymethyl methacrylate may be a homopolymer or copolymer of methyl methacrylate. The copolymer of methyl methacrylate may be a copolymer obtained by polymerizing methyl methacrylate with at least one component selected from the group consisting of methyl acrylate, ethyl acrylate, butyl acrylate and styrene. Here, the composition ratio of the comonomers constituting the copolymer is not particularly limited in the range using methyl methacrylate as a main component, but preferably 80 to 99% by weight of methyl methacrylate and 1 to 20% by weight of comonomer. It can superpose | polymerize in ratio of. More preferably, polymerization at a ratio of 85 to 97% by weight of methyl methacrylate and 3 to 15% by weight of comonomer is preferable since the heat resistance and scratch resistance are not lost.

The weight average molecular weight of the polymethylmethacrylate used in the present invention is preferably 60,000 to 150,000, more preferably 70,000 to 130,000. When the weight average molecular weight of the polymethyl methacrylate exceeds 150,000, the impact strength is good, but there is a problem in processing the polymethyl methacrylate due to the increase in the melt viscosity of the polymethyl methacrylate. On the other hand, when the weight average molecular weight of the polymethyl methacrylate is less than 60,000, the melt viscosity of the polymethyl methacrylate is good, so that the processability of the polymethyl methacrylate is good, but mechanical properties such as impact strength and tensile strength are remarkable. Degrades.

The alkyd may be prepared by mixing a polybasic acid, a polyhydric alcohol, and an oil or fat. According to an embodiment of the present invention, the polybasic acid includes aliphatic, aromatic, saturated alicyclic, unsaturated carbonic acid, esterifiable derivatives, etc., and the content thereof is 1 to 20% by weight, preferably 3 to 8% by weight based on the alkyd. %to be. If the content of the polybasic acid is less than 1% by weight, the hardness and viscosity are lowered, and if it exceeds 20% by weight, the hardness is high and the workability tends to be inferior.

Examples of polyhydric alcohols used for the preparation of the alkyd include ethylene glycol, 1,3 or 1,2-propanediol, 1,4, 1,3 or 1,2-butanediol, 2-ethylpropanediol-1,3 , 2-ethylhexanediol-1,3, neopentylglycol, 1,6-hexanediol, 1,4 or 1,2-cyclohexanediol, 1,4-bis-hydroxymethyl-cyclohexane, or adipic acid Alcohols such as bis-ethylene glycol ester, and the like, but are not limited thereto. The polyhydric alcohol is used in 7 to 20% by weight, preferably 12 to 16% by weight relative to the alkyd-based resin, less than 7% by weight may be less flexible, higher viscosity may lower workability. Conversely, if it exceeds 20% by weight, the hardness and viscosity are lowered and the drying is slowed.

Fatty acids used for the preparation of the alkyd are vegetable and animal oils, coconut, coconut, tung, olive, soybean, cottonseed, saflower, dihydrate carbon Fats such as oils and synthetic fatty acids made from a combination of isomers with fatty acids, pork oil, tallow, trane, deoiled fatty acids (tofa), and natural unsaturated oils. Saturated fatty acids commonly used are coconut fatty acids, such as 1-ethylhexanoic acid and 3,4,4, -trimethylolhexanoic acid, and palmitic acid, stearic acid, and synthetic saturated fatty acids. The amount of the fatty acid or oil used is 10 to 70% by weight, preferably 20 to 50% by weight, based on alkyd, and less than 10% by weight, the flexibility is low, the viscosity is high, and the reaction is easily gelled. If it exceeds 70% by weight, hardness and viscosity are lowered, which may cause water resistance.

The phenol includes a thermosetting synthetic resin obtained by heat condensation of phenol and formaldehyde, and includes phenol, o, m or p-cresol, 2,4-xylenol, 3,4-xylenol, 2,5-xyl Nol, cardanol, p-tert-butyl phenol, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (3-bromo-4-hydroxyphenyl) -propane, 2,2- Bis (3,5-dichloro-4-hydroxyphenyl) propane, 2,2-bis (3-chloro-4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) -methane, bis (4-hydroxy Oxyphenyl) sulfone, bis (4-hydroxyphenyl) sulfide, riscinol, hydroquinone and the like, but is not limited thereto.

The unsaturated polyester may be prepared by a crosslinking reaction by condensation of an unsaturated polybasic acid and a polyhydric alcohol, and polymerization by addition of a polymerizable unsaturated monomer such as styrene and a curing agent, but is not limited thereto.

The polyvinyl alcohol may generally be obtained by hydrolyzing polyvinyl acetate and the like, but is not limited thereto. The polyvinyl alcohol includes a copolymer of vinyl alcohol such as an ethylene-vinyl alcohol copolymer or a partially saponified ethylene-vinyl alcohol copolymer and a monomer copolymerizable with vinyl alcohol. Moreover, the modified polyvinyl alcohol in which carboxylic acid etc. were introduce | transduced in part is included. In this invention, these polyvinyl alcohol may be used individually by 1 type, and may be used in combination of 2 or more type.

(3) silane coating agent

The silane coating agent of the ultralight polymer concrete composition according to the present invention serves to coat the fine particles. The silane coating agent is preferably contained in 2 to 8% by weight can express the physical properties required in the present invention, it is more preferably contained in 2 to 5% by weight.

The silane coating agent may include a silane compound. Silane is the simplest silicone monomer, and has the organic functional group and the hydrolyzable group that can react with the organic material and the organic material in the same molecule can combine the organic material and the inorganic material. Through this, it is possible to improve the mechanical strength, water resistance, adhesiveness, and the like of the ultralight polymer concrete composition of the present invention, increase wear resistance and weather resistance through surface coating, and improve electrical properties and physical strength. The silane compounds include, but are not limited to, alkoxy silanes, amino silanes, epoxy silanes, acrylic silanes, mercapto silanes, fluorine silanes, methoxy silanes, vinyl silanes, chloro silanes, silazanes, and the like.

(4) strength enhancers

Strength enhancer of the ultralight polymer concrete composition according to the present invention serves to improve the initial compressive strength of the ultralight polymer concrete composition. The strength enhancer is preferably contained in 3 to 8% by weight can express the physical properties required in the present invention, it is more preferably contained in 3 to 5% by weight.

Strength enhancer of the present invention may include one or more selected from the group consisting of calcium carbonate, calcium chloride, calcium hydroxide, gypsum, but is not limited thereto. The calcium carbonate and gypsum are pore filling materials that fill the pores between tissues of the composition, thereby densifying connective tissue, thereby improving compressive strength. Calcium hydroxide functions to ensure high performance (high strength, high durability, high density) of connective tissue through the pozzolanic reaction, and calcium chloride serves to promote the binding reaction of the composition.

(5) Inorganic hollow bodies

The inorganic hollow body of the ultralight polymer concrete composition according to the present invention promotes weight reduction of the ultralight polymer concrete composition. Inorganic hollow bodies according to an embodiment of the present invention are hollow particles having a hollow structure, and the term "hollow" as used herein is to be understood to mean an empty space inside surrounded by an inorganic composite forming a shell. Can be. The inorganic hollow body is preferably contained in 10 to 25% by weight can be expressed in the physical properties required in the present invention, more preferably contained in 10 to 20% by weight, it is preferable that the micron unit is porous.

Inorganic hollow bodies of the present invention include vermiculite, diatomite, kaolin, bentonite, bauxite, ball clay, perlite, and attapulgite ( Attapulgite, quartz, glass bubble, silicon, and zeolite may be selected from the group consisting of, but is not limited thereto.

In addition, the inorganic hollow body includes an inorganic hollow body coated with a silane compound. The inorganic hollow body coated with the silane compound may not only reinforce the surface of the particle due to the surface coating effect, but also prevent the resin particles from flowing into the hollow of the inorganic hollow body during composition preparation. Silane compounds include alkoxy silanes, amino silanes, epoxy silanes, acrylic silanes, mercapto silanes, fluorine silanes, methoxy silanes, vinyl silanes, chloro silanes, silazanes, and the like, which are used as the silane coating agent. no.

(6) Additives

Ultra-light polymeric concrete composition according to the present invention may include additives such as impact modifiers, antibacterial agents, mold release agents, thermal stabilizers, antioxidants, light stabilizers, colorants, stabilizers, pigments, dyes and opacifiers, The amount used is not limited, but may be 0.01 to 10% by weight, preferably 0.05 to 10% by weight.

On the other hand, the present invention provides a molded article obtained by curing the ultralight polymer concrete composition. The molded article has a compressive strength of 50 to 90 MPa, preferably 65 to 90 MPa, a flexural strength of 15 to 25 MPa, preferably 20 to 25 MPa, a tensile strength of 8 to 20 MPa, preferably 12 to 20 MPa, and 5 to 6 MPa, preferably For example, it exhibits excellent physical properties such as adhesion strength of 5.3 to 6 MPa, and its specific gravity is 0.5 to 0.8, preferably 0.6 to 0.65 depending on the content of the inorganic hollow body.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following examples are only examples of the present invention and the present invention is not necessarily limited thereto.

Example

In order to evaluate the performance of the ultralight polymer concrete composition of the present invention, the compositions of Examples 1 to 4 were prepared at the blending ratios shown in Table 1 below, and the compressive strength, flexural strength, and tensile strength according to the blending ratio of each composition according to KS F 2476. Strength and bond strength test (daily basis) was performed and the results are shown in Table 2 below.

From the results of Table 2, it was found that the ultralight polymer concrete compositions according to Examples 1 to 4 exhibited excellent physical properties of compressive strength of 50 MPa or more, flexural strength of 15 MPa or more, tensile strength of 8 MPa or more, and adhesion strength of 5 MPa or more. In particular, in the compositions according to Examples 2 to 4, it can be seen that the marked physical properties such as compressive strength of 65MPa or more, flexural strength of 20MPa or more, tensile strength of 12MPa or more, and adhesion strength of 5.3MPa or more.

In addition, the compositions of Examples 5 to 8 were prepared at the blending ratios shown in Table 3 below, and the compressive strength and specific gravity tests were performed according to the blending ratios of the respective compositions according to KS F 2476, and the results are shown in Table 4 below. .

From the results of Table 4, it can be seen that the ultralight polymer concrete composition according to Examples 5 to 8, in particular, the difference in specific gravity and compressive strength depending on the content of the inorganic hollow body. Specifically, it can be seen that the content of the inorganic hollow body is 10 to 20% by weight, among which 15% by weight is the most excellent physical property.

As described above, the ultra-light polymer concrete composition according to the present invention can not only cast in-situ but also precast, thereby reducing various costs, popularizing structural ultra-light polymer concrete, compressive strength of 50 to 90 MPa, and 15 to 25 MPa. Due to its excellent properties such as bending strength, tensile strength of 8 ~ 20MPa, and adhesion strength of 5 ~ 6MPa, it provides not only excellent construction quality but also ease of construction and economy.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, It is to be understood that the invention may be practiced within the scope of the appended claims.

Claims (11)

As a composition comprising 50 to 60% by weight of the first resin, 15 to 20% by weight of the second resin, 2 to 8% by weight of the silane coating agent, 3 to 8% by weight of the strength enhancer, and 10 to 25% by weight of the inorganic hollow body,
The first resin includes at least one selected from the group consisting of polyurethane and polyurethane acrylate, and the second resin is polymethyl methacrylate, methyl methacrylate, alkyd, phenol, unsaturated polyester and polyvinyl alcohol At least one selected from the group consisting of, wherein the silane coating agent is a group consisting of alkoxy silane, amino silane, epoxy silane, acrylic silane, mercapto silane, fluorine silane, methoxy silane, vinyl silane, chloro silane and silazane At least one silane compound selected from the above, the strength enhancer comprises at least one selected from the group consisting of calcium carbonate, calcium chloride, calcium hydroxide and gypsum, the inorganic hollow body is vermiculite, diatomite, kaolin ( kaolin, bentonite, bauxite, ball clay ), Perlite, attapulgite, quartz, quartz, glass bubble, silicon and zeolite, and at least one selected from the group consisting of Ultralight Polymer Concrete Compositions. delete delete delete delete delete The method of claim 1,
The inorganic hollow body is super lightweight polymer concrete composition, characterized in that the coating treatment with a silane compound. 8. The method of claim 1 or 7,
The ultralight polymer concrete composition is characterized in that it further comprises at least one additive selected from the group consisting of impact modifiers, antibacterial agents, mold release agents, heat stabilizers, antioxidants, light stabilizers, colorants, stabilizers, pigments, dyes and opacifying agents Polymer concrete composition. A molded article obtained by curing the ultralight polymer concrete composition according to claim 1, wherein the molded article has a compressive strength of 50 to 90 MPa, a flexural strength of 15 to 25 MPa, a tensile strength of 8 to 20 MPa, and an adhesion strength of 5 to 6 MPa. Molded article characterized in that. The method of claim 9,
Molded products with a specific gravity of 0.5 to 0.8. delete