CN113039228A

CN113039228A - Polyurethane foam and method for producing polyurethane foam

Info

Publication number: CN113039228A
Application number: CN201980075160.3A
Authority: CN
Inventors: 折笠理加; 桐山卓也
Original assignee: Inoac Corp; Rogers Inoac Corp
Current assignee: Inoac Corp; Rogers Inoac Corp
Priority date: 2018-11-15
Filing date: 2019-11-07
Publication date: 2021-06-25
Also published as: JP2020084173A; JP7293047B2; KR20210091151A

Abstract

The polyurethane foam of the present disclosure is obtained from a polyurethane raw material containing a polyol component and a polyisocyanate component, and a foaming gas. The polyurethane raw material contains hydrophobic silica and light calcium carbonate, wherein the hydrophobic silica is a foam holding agent for holding foam, and the light calcium carbonate is 10 parts by weight or more relative to 100 parts by weight of the polyol component.

Description

Polyurethane foam and method for producing polyurethane foam

Technical Field

The present disclosure relates to polyurethane foams and methods of making the same.

Background

Patent document 1 discloses a mechanical foaming method (for example, paragraphs [0008] to [0009 ]) as a method for producing a polyurethane foam. In the mechanical foaming method, bubbles are formed by mechanically and forcibly mixing an inert gas into a polyurethane raw material containing a polyol component, a polyisocyanate component, a foam stabilizer, and the like.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2009-13304

Disclosure of Invention

Problems to be solved by the invention

In the mechanical foaming method, since the density, hardness, and the like of the polyurethane foam can be easily adjusted, a polyurethane foam suitable for various applications can be produced. As an example thereof, a polyurethane foam used for an impact absorbing material is known, but further improvement of impact absorbability is required.

Means for solving the problems

One aspect of the present disclosure is a polyurethane foam obtained from a polyurethane raw material containing a polyol component and a polyisocyanate component, and a foaming gas, wherein the polyurethane raw material contains hydrophobic silica that is a foam retaining agent for retaining foam and light calcium carbonate, and the light calcium carbonate is 10 parts by weight or more and 180 parts by weight or less and the hydrophobic silica is 0.6 parts by weight or more relative to 100 parts by weight of the polyol component in the polyurethane raw material.

Another aspect of the present disclosure is a method of making a polyurethane foam of the previous aspect, wherein,

the polyurethane foam is obtained from the polyurethane raw material and the foaming gas by a mechanical foaming method.

Drawings

FIG. 1 is a schematic view showing a molecular structure in the vicinity of the surface of hydrophobic silica contained in a polyurethane foam according to an embodiment.

Detailed Description

The polyurethane foam of the present embodiment can be obtained from a polyurethane raw material containing a polyol component, a polyisocyanate component and a foam stabilizer, and a gas for foam generation. It is preferable that water and a foaming agent are not blended in the polyurethane raw material.

As the polyol component, polyether polyols, polyester polyols, polyether polyol obtained by copolymerizing polyether polyol and polyester polyol, and the like can be used. Further, a polymer polyol may be used in combination for the purpose of producing a foam having a sufficient tensile strength or the like. The polymer polyol is obtained by graft polymerizing an ethylenically unsaturated compound such as acrylonitrile, styrene, and methyl methacrylate onto a polyether polyol in an amount of 10 to 40% by mass, preferably 15 to 30% by mass, in terms of solid content of the polymer polyol, and various polymer polyols can be used without particular limitation. The above-mentioned various polyols may be used alone or in combination of two or more.

The polyol component may include a plant-derived polyol in addition to the above-mentioned polyols. Examples of the plant-derived polyol include castor oil-based polyols, soybean oil-based polyols, palm oil-based polyols, cashew oil-based polyols, and the like. Examples of the castor oil-based polyol include castor oil, a reaction product of castor oil and a polyol, and an esterification reaction product of castor oil fatty acid and a polyol. Examples of the polyol to be reacted with castor oil or castor oil fatty acid include dihydric polyols such as ethylene glycol, diethylene glycol and propylene glycol, and trihydric or higher polyols such as glycerin, trimethylolpropane, hexanetriol and sorbitol. The blending ratio of the castor oil polyol to the total polyol component is preferably 20 to 80% by mass. Examples of the soybean oil-based polyol include a polyol derived from soybean oil, for example, a reaction product of soybean oil and a polyol, and an esterification reaction product of soybean oil fatty acid and a polyol. As the polyol to be reacted with soybean oil or soybean oil fatty acid, the same polyol as in the case of the above-mentioned castor oil can be used. Palm oil-based polyols, cashew oil-based polyols, and the like are also the same as those of soybean oil-based polyols. The various polyols exemplified above as plant-derived polyols may be used alone or in combination of two or more.

As the polyisocyanate component, Tolylene Diisocyanate (TDI), crude TDI, 4' -diphenylmethane diisocyanate (MDI), crude MDI, and the like are often used. Further, it is possible to use: 1, 6-Hexamethylene Diisocyanate (HDI), crude HDI, 1, 5-naphthalene diisocyanate, p-phenylene diisocyanate, 2, 4-trimethylhexamethylene diisocyanate, 2,4, 4-trimethylhexamethylene diisocyanate, 4,4 ' -dicyclohexylmethane diisocyanate, m-xylene diisocyanate, hexamethylene diisocyanate, hydrogenated MDI, isophorone diisocyanate, 2, 4-toluene diisocyanate, 2, 6-toluene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 2,4 ' -diphenylmethane diisocyanate, 2 ' -diphenylmethane diisocyanate, xylylene diisocyanate, 3 ' -dimethyl-4, 4 ' -biphenyl diisocyanate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl, 3,3 '-dimethoxy-4, 4' -biphenyl diisocyanate, cyclohexane-1, 4-diisocyanate, methylcyclohexane diisocyanate, butane-1, 4-diisocyanate, isopropylidene diisocyanate, methylene diisocyanate, lysine isocyanate, 1-methylbenzene-2, 4, 6-triisocyanate, 1,3, 5-trimethylbenzene-2, 4, 6-triisocyanate, biphenyl-2, 4,4 '-triisocyanate, diphenylmethane-2, 4, 4' -triisocyanate, methyldiphenylmethane-2, 6,4 '-triisocyanate, 4, 4' -dimethyldiphenylmethane-2, 2 ', 5, 5' tetraisocyanate, triphenylmethane-4, 4 ', 4' -triisocyanate, polymethylene polyphenyl isocyanate and other aromatic and aliphatic polyisocyanates. In addition to these, a prepolymer type polyisocyanate may also be used. The polyisocyanate may be used alone or in combination of two or more. The polyisocyanate component is blended so that the isocyanate index is 80 to 120, preferably 90 to 110.

Particularly useful are silicone surfactants as foam stabilizers. Preferred silicone surfactants are those consisting essentially of SiO₂(silicate) units and (CH)₃)₃SiO_0.5(trimethylsiloxy) units, the molar ratio of silicate units to trimethylsiloxy units being 0.8: 1-2.2: 1. preferably 1: 1-2.0: 1. other preferred silicone surfactants are partially crosslinked siloxane-polyoxyalkylene block copolymers and mixtures thereof, the siloxane blocks and polyoxyalkylene blocks being bonded to carbon via silicon or to oxygen-carbon bonds via silicon. The siloxane blocks comprise hydrocarbon-siloxane groups, each block bonded by the aforementioned bonds having on average at least 2 valent silicon. At least a part of the polyoxyalkylene block is composed of an alkylene oxide and is polyvalent. That is, at least a part of the polyoxyalkylene block has at least one of carbon having a valence of at least 2 and oxygen bonded to carbon in each block bonded by the aforementioned bond. The remaining polyoxyalkylene block is composed of alkylene oxide and is monovalent. That is, the remaining polyoxyalkylene block has only at least one of carbon having a valence of 1 and oxygen bonded to carbon in each block bonded by the aforementioned bond. General organopolysiloxane-polyoxyalkylene block copolymers such as the organopolysiloxane-polyoxyalkylene block copolymers described in U.S. Pat. Nos. 2,834,748, 2,846,458, 2,868,824, 2,917,480, and 3,057,901 may also be used. The amount of the silicone polymer used as the foam stabilizer may vary within a wide range, and for example, may vary from 0.5 to 10% by mass or more relative to the amount of the active hydrogen component. Preferably, the amount of silicone copolymer present in the foam formulation varies from 1.0 to 6.0 mass% on the same basis.

In the present embodiment, the polyurethane raw material contains inorganic silica as a foam retaining agent for retaining foam. As the foam retaining agent, hydrophobic silica is particularly preferable. The hydrophobic silica is formed, for example, by subjecting particles of silica to surface treatment (hydrophobic treatment) with a hydrophobic treatment agent.

The silica as a matrix before the surface treatment with the hydrophobizing agent (hereinafter referred to as matrix silica) may be wet silica (for example, precipitated silica, gel silica, or the like) or dry silica (for example, fumed silica or the like). The base silica has a plurality of hydrophilic silanol groups on the surface and is hydrophilic.

The hydrophobizing agent is preferably a silicone oil. Examples of the silicone oil include: dimethyl silicone oil, methylphenyl silicone oil, chloro silicone oil, chlorophenyl silicone oil, methyl hydrogen-containing silicone oil, amino-modified silicone oil, epoxy-modified silicone oil, fatty acid ester-modified silicone oil, carboxylic acid-modified silicone oil, polyether-modified silicone oil, alkyl-modified silicone oil, and the like. As the hydrophobizing agent, for example, a silane coupling agent, an alkyl silazane (e.g., hexamethyldisilazane, vinyl silazane, etc.), or the like can be used.

A schematic diagram of a hydrophobic silica (symbol 20) using a silicone oil as a hydrophobizing treatment agent is shown in fig. 1. In the example shown in the figure, as the silicone oil having a surface treated with the base silica (reference numeral 21), a dimethyl silicone oil (dimethylpolysiloxane) was used.

It is considered that in the surface treatment with silicone oil, for example, by cleaving siloxane bonds (-Si-O-Si-) in the silicone oil by heating or the like, an organic silicon compound having silanol groups (-Si-O-H) (for example, organopolysiloxane, trialkylsinol, or the like) is produced (formula (1)), and the organic silicon compound and the base silica are siloxane-bonded by dehydration condensation of the silanol groups (formula (2)). As described above, when the surface of the matrix silica is treated with the hydrophobizing agent, the number of hydrophilic silanol groups on the surface of the matrix silica is decreased by the reaction (the hydrophobic groups are increased on the surface of the silica), and thus it is considered that hydrophobicity can be imparted to the silica. In the formulae (1) and (2), R represents an organic group, and may be the same or different. In the hydrophobic silica, the silanol groups on the surface of the base silica may be coated with only the hydrophobic treatment agent without reacting with the hydrophobic treatment agent.

[ solution 1]

[ solution 2]

The hydrophobic silica preferably has a methanol wettability (M value) of 20% or more, more preferably 40% or more. The M value is a volume% of methanol to the whole mixed solution when the silica powder is put into the mixed solution of water and methanol, at which the silica powder starts to settle. Higher M values indicate higher hydrophobicity. The M value of the matrix silica which had not been subjected to the hydrophobization treatment was 0. Specifically, when measuring the M value, a solution obtained by adding 0.1g to 0.2g of silica powder to 5mL of a mixed solution of water and methanol was shaken 2 times to confirm whether or not the silica powder was precipitated.

The hydrophobic silica preferably has a DBA (di-n-butylamine) adsorption amount of 100 mmol/kg or less, more preferably 60 mmol/kg or less. The DBA adsorption amount means an amount of DBA adsorbed on silanol groups on the surface of silica. A low amount of DBA adsorption means that the silanol groups on the surface of the silica are changed to siloxane bonds or coated with silicone oil, and therefore, DBA is hardly adsorbed, and generally means high hydrophobicity. The DBA adsorption amount of the base silica which has not been subjected to the hydrophobization treatment is 200 mmol/kg or more. Specifically, the DBA adsorption amount can be obtained as follows. To 250mg of the dried silica powder, 50mL of an N/500 di-N-butylamine solution (petroleum ether solvent) was added, and the mixture was shaken for 1 hour. Then, a solution obtained by adding 10mL of ethanol to 25mL of the supernatant thereof was titrated with an N/100 perchloric acid solution (acetic anhydride solvent) using a potential difference automatic titrator, and the titration value was defined as a (mL). Further, a solution (blank) obtained by adding 10mL of ethanol to 25mL of the N/500 di-N-butylamine solution was titrated by a potential difference automatic titrator in the same manner as described above, and the titration value was B (mL). Then, the DBA adsorption amount (mmol/kg) was calculated from the following formula (α). Wherein f is the titration rate of the N/100 perchloric acid solution.

DBA adsorption capacity 80 × (B-a) × f (α)

The hydrophobic silica preferably has a dissolution rate of the hydrophobic treatment agent into toluene of less than 0.2% by mass relative to the mass of the hydrophobic silica. The dissolution rate is a ratio of the amount of the hydrophobic silica eluted at a time of 24 hours at 20 ℃ to the mass of the hydrophobic silica before dispersion, when the hydrophobic silica was dispersed in toluene at a concentration of 2%. It is considered that the lower the elution rate of the hydrophobizing agent into toluene, the less the hydrophobizing agent does not react with the silanol groups on the silica surface.

BET specific surface area of 100m per 100 parts by weight²The hydrophobic silica preferably contains 3 to 9 parts by weight of silicone oil per g of base silica. The hydrophobic silica preferably has a particle diameter of 10 to 400 μm.

The hydrophobic silica preferably has a contact angle of water with respect to the hydrophobic silica of 145 degrees or more, more preferably 160 degrees or more. The contact angle of water with hydrophobic silica can be measured by forming a powder of hydrophobic silica into a film or the like and dropping a water droplet on the surface thereof.

As the hydrophobic silica, commercially available products can be used. Examples of such commercially available products include: "Nipsil (registered trademark)" SS series (for example, SS-10, SS-20, SS-40, SS-50A, SS-70, SS-80K, SS-80S, SS-100, SS-115, and SS-178) manufactured by Tosoh silica K.K.; "Nipgel (registered trademark)" series (e.g., AY-200, AZ-400, BZ-400, CY-200, etc.) manufactured by Tosoh silica K.K.; "AEROSIL (registered trademark)" series manufactured by EVONIC, HDK (registered trademark) "series manufactured by Asahi Kawakki Silicone K.K.," CAB-O-SIL (registered trademark) "series manufactured by Cabot corporation, and" QSG "series manufactured by shin-Etsu chemical industries, Ltd. One of them may be used alone, or two or more of them may be used in combination.

The foaming gas is not particularly limited as long as it is inert to the polyol component and the polyisocyanate component, and may be an inert gas such as nitrogen or argon, or may be dry air.

The polyurethane raw material may contain a filler, a catalyst, a crosslinking agent, and the like in addition to the polyol component, the polyisocyanate component, the foam stabilizer, and the foam retaining agent.

Examples of the filler include a thickener, a colorant, and an antistatic agent. The polyurethane raw material of the present embodiment contains light calcium carbonate as a functional filler. The light calcium carbonate preferably has a particle size of 0.08 to 5.0. mu.m.

The catalyst may be an amine-based catalyst or a metal catalyst (organometallic compound-based catalyst) for polyurethane foam, either alone or in combination. The amine catalyst includes monoamine compounds, diamine compounds, triamine compounds, polyamine compounds, cyclic amine compounds, alcohol amine compounds, ether amine compounds, and the like, and one of them may be used alone, or two or more thereof may be used in combination. The metal catalyst includes an organotin compound, an organobismuth compound, an organolead compound, an organozinc compound, and the like, and one of them may be used alone, or two or more thereof may be used in combination.

Examples of the crosslinking agent include low-molecular compounds having 2 to 4 active hydrogen-containing groups capable of reacting with an isocyanate group and having a number average molecular weight of 50 or more and 800 or less. Examples of the low-molecular-weight compound used as a crosslinking agent include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1, 4-butanediol, 1, 6-hexanediol, neopentyl glycol, glycerin, trimethylolpropane, triethanolamine, pentaerythritol, and the like, and one kind or two or more kinds of them may be used in combination.

The polyurethane foam of the present embodiment is produced as follows: the polyurethane raw material is mixed and stirred with the foaming gas, and then the mixture is heated to react and cure the polyol component and the polyisocyanate component. Specifically, the polyurethane raw material is supplied into the chamber, and the foaming gas is also supplied into the chamber, and the polyurethane raw material and the foaming gas are stirred by a stirrer such as an oxter mixer or a hobart mixer to be mixed with each other in a gas-liquid state. At this time, bubbles are formed in the gas-liquid mixture. The gas-liquid mixture is then discharged into a forming die or onto a carrier film. Then, the gas-liquid mixture is heated to a desired temperature, and the polyol component and the polyisocyanate component are reacted and cured, thereby producing a polyurethane foam. When the gas-liquid mixture is discharged into the mold, the mixture is cooled and then taken out of the mold, thereby obtaining a polyurethane foam having a predetermined shape. When the gas-liquid mixture was discharged onto the carrier film, after cooling, the carrier film was removed, and the obtained foam sheet was punched out to obtain a polyurethane foam of a predetermined shape.

When the amount of light calcium carbonate added is small, the foamability when the polyurethane raw material is mixed and stirred with the foaming gas is deteriorated, and bubbles are less likely to be formed in the gas-liquid mixture. Further, when the amount of the light calcium carbonate added is increased, the foam-retaining property is deteriorated, and when the amount is further increased, the raw material may become pasty and stirring may become difficult. The amount of precipitated calcium carbonate in the present embodiment is 10 parts by weight or more and 180 parts by weight or less based on 100 parts by weight of the polyol component. The lower limit of the amount of light calcium carbonate to be blended is preferably 40 parts by weight or more based on the same reference. The upper limit of the amount of precipitated calcium carbonate is preferably 150 parts by weight or less, more preferably 140 parts by weight or less, and still more preferably 100 parts by weight or less.

In addition, even if the light calcium carbonate is 10 parts by weight or more, when the hydrophobic silica is not contained in the polyurethane raw material, the retention of the foam is deteriorated. The lower limit of the amount of hydrophobic silica is 0.6 parts by weight or more, preferably 0.8 parts by weight or more, and more preferably 1 part by weight or more, based on 100 parts by weight of the polyol component. The upper limit of the amount of hydrophobic silica is preferably 5 parts by weight or less, more preferably 4 parts by weight or less, and particularly preferably 3 parts by weight or less, based on 100 parts by weight of the polyol component. When the amount of hydrophobic silica is more than 5 parts by weight and when the amount of hydrophobic silica is less than 0.8 part by weight, the appearance may be deteriorated after molding.

[ Experimental example ]

Polyurethane foams were produced from the polyurethane raw materials of experimental examples 1 to 15 shown in tables 1 and 2, and the foaming property, the appearance after molding, the impact absorbability and the hardness were evaluated for each experimental example.

The components shown in tables 1 and 2 are as follows. The amounts of the respective components in the table are indicated by parts by weight.

A polyol component; the production was carried out using a polyether polyol (trade name "Sannix GP-600" manufactured by Sanyo chemical industries Co., Ltd.) and a castor oil polyol (trade name "URIC Y-406" manufactured by Ito oil Co., Ltd.). In tables 1 and 2, the polyol component obtained by adding together the polyether polyol and the castor oil polyol was 100 parts by weight.

A polyisocyanate component; manufactured by BASF INOAC polyurethane corporation, under the trade name "FOAMLITE MI" (isocyanate index of 105)

A foam retention agent; (1) untreated silica (hydrophilic matrix silica not subjected to hydrophobization treatment): manufactured by Tosoh silica K.K., under the trade name "Nipsil KQ" (M value of 0%), (2) hydrophobic silica (hydrophobized silica): wet-process silica, manufactured by Tosoh silica K.K., under the trade name "Nipsil SS-80K" (M value: 45%)

A foam stabilizer; silicone surfactant: manufactured by Momentive Inc., trade name "L-5614", 10 parts by weight,

a catalyst; 0.1 part by weight of tin 2-ethylhexanoate

Light calcium carbonate; manufactured by Baishi Industrial Co., Ltd., trade name "Silver W"

Heavy calcium carbonate; beibei Kai Kabushiki Kaisha, trade name "BF 200" (Experimental example 12), Asahi mineral powder Kabushiki Kaisha, trade name "S tancal" (Experimental example 13)

An antioxidant; 0.13 part by weight of IRGANOX1135 manufactured by BASF Japan K.K

A moisture absorbent; 2.69 parts by weight of a polymer having a Molecular Sieve 3APOWDER tradename manufactured by Union Showa Co

In tables 1 and 2, the particle size of calcium carbonate means the average particle size [ μm ] of the light or heavy calcium carbonate used in each experimental example. The average particle diameter is a particle diameter value in which a volume-based cumulative fraction in a particle diameter distribution obtained by a laser diffraction scattering method according to JIS R1629-1997 (the specific surface area is determined by an air permeability method according to JIS M8511: 2014) is 50%. The silica particle size means an average particle size [ μm ] of the untreated silica or the hydrophobic silica used in each experimental example. The average particle diameter is a particle diameter in which a cumulative percentage on a volume basis in a particle diameter distribution obtained by a Coulter Multisizer (manufactured by Beckmann Coulter Co., Ltd.; an orifice tube having a diameter of 30 μm is used) is 50%. Specifically, a small amount of untreated silica or hydrophobic silica was placed in about 0.5mL of ethanol and subjected to ultrasonic dispersion, and further placed in about 20mL of an electrolytic solution (ISOTON-2, manufactured by beckmann coulter corporation) and subjected to ultrasonic dispersion for 40 seconds, and the particle size distribution of the dispersion was measured.

In the production of polyurethane foam, a polyurethane raw material is discharged onto a carrier film continuously fed at a speed of 1 to 15 m/min to form a film having a thickness of 0.2 to 10 mm0mm foam sheet. For the foaming gas, dry air was used at a density of 150kg/m³～700kg/m³The flow rate of (2).

The evaluation of foamability was specifically carried out as follows: the polyurethane raw material and isocyanate were stirred for 2 minutes while air was mixed in with a hand-held mixer, and then the density (apparent density) of the cured sample was less than 290kg/m³In the case of this, the evaluation is "O" (more preferably 280 kg/m)³Hereinafter), the density (apparent density) was 290kg/m³When the above results were obtained, the evaluation was "X". Further, regarding the evaluation of the appearance after molding, the molded sample was visually checked, and evaluated as "o" when the surface was smooth and there were no pinholes, voids, etc., and evaluated as "x" when the surface of the molded sample was rough or pinholes, voids, etc., occurred. If the material was pasty and could not be molded, the evaluation was "-".

The method for evaluating the impact absorbability was performed by an impact test according to EN1621 of the CE standard. Specifically, a sample having a thickness of 20mm was prepared, and 5kg of an iron ball was dropped from a height of 1m above the sample at room temperature of 23 ℃. Then, the impact transmitted to the lower side of the sample was measured by an impact sensor, and the impact absorbability was evaluated based on the measured value.

The hardness was evaluated by 25% compressive hardness (25% CLD (Compression Load Deflection). 25% compression hardness based on JIS K6254: 2010, test by method D. In this test, a polyurethane foam having a cylindrical shape with a diameter of 50mm was used as a test sample, and the entire surface of a circular pressing surface with a diameter of 50mm of the polyurethane foam was pressed, and the polyurethane foam was compressed in the axial direction at a speed of 1.0 mm/min until a compression strain of 30% of the axial length before compression was generated (until the axial length reached 70% before compression). At this time, a relation (compression force-deformation curve) between the compression force and the compression strain was recorded, and from this relation (curve), the compression force (N) was obtained when the compression strain was 25% with respect to the axial length of the polyurethane foam before compression (when the axial length was 75% before compression). Then, the compressive force was divided by the cross-sectional area of the polyurethane foam (i.e., the area of the pressed surface: 25X the circumference ratio (mm)²) Thereby to obtainThe 25% compressive hardness (MPa) (formula (. beta.)). In this test, repeated compression (pre-compression) of the polyurethane foam was not performed.

25% compression hardness

Compressive force at 25% compressive strain/cross-sectional area (β) of polyurethane foam

In the comprehensive evaluation, a sample having poor foamability (× or-), a sample having good foamability (°) and good appearance after molding (satisfactory) and having an impact absorption (measured value by an impact sensor) of 8kN or less were evaluated as "x", and a sample other than these samples were evaluated as "x".

As is clear from the results in tables 1 and 2, when the amount of precipitated calcium carbonate is less than 10 parts by weight based on 100 parts by weight of the polyol component (experimental example 5), the foaming property is poor (x). The main reason for this is that when the amount of light calcium carbonate blended is small, the absolute amount of the nucleating agent in the raw material is reduced, and foaming is likely to be deteriorated. In addition, when heavy calcium carbonate was contained instead of light calcium carbonate, foaming was poor (x) (experimental examples 12 and 13).

Even if the amount of light calcium carbonate added is 10 parts by weight or more, when the hydrophobic silica is not contained (experimental examples 1 and 14), the foaming property and the appearance after molding are poor (x). In addition, in the case where an untreated silica (i.e., a hydrophilic silica) which was not subjected to hydrophobization treatment was contained instead of the hydrophobic silica (experimental example 14), the foaming property and the appearance after molding were poor (x). From this fact, it is considered that when the hydrophobic silica is contained, the foam integrity is improved and the foam retainability is improved in addition to the foaming action as the nucleating agent.

In addition, when the light calcium carbonate is more than 140 parts by weight (experimental example 8) with respect to 100 parts by weight of the polyol component, the impact absorbability is somewhat lowered. This is considered to be caused by a slight deterioration in foam retentivity when the amount of precipitated calcium carbonate compounded is large. When the amount of light calcium carbonate added is 200 parts by weight or more (experimental example 9), the raw material becomes pasty and stirring becomes difficult.

In the case where hydrophobic silica is contained as the foam retaining agent as described above, even if precipitated calcium carbonate is contained as the functional filler, foam is easily formed. When the amount of light calcium carbonate added is 10 parts by weight or more and 140 parts by weight or less based on 100 parts by weight of the polyol component (experimental examples 2, 3 and 7), the impact absorbability is 8kN or less, and high impact absorbability is exhibited. Even if the amount of precipitated calcium carbonate blended is 10 parts by weight or more and 140 parts by weight or less, the appearance after molding is deteriorated when the amount of hydrophobic silica blended is more than 5 parts by weight (experimental example 4). It is considered that the deterioration of the appearance after molding is caused by the deterioration of curability when the amount of hydrophobic silica blended is large. In addition, when the amount of hydrophobic silica is less than 0.6 parts by weight (experimental example 15), the appearance after molding is also deteriorated.

In tables 1 and 2, experimental examples 2 to 4,6 to 8, 10 and 11 correspond to "examples", and experimental examples 1,5, 9 and 12 to 15 correspond to "comparative examples".

Hereinafter, the feature groups extracted in the above-described embodiments and experimental examples will be described while showing effects and the like as necessary.

[ feature 1]

A polyurethane foam obtained from a polyurethane raw material containing a polyol component and a polyisocyanate component and a gas for foam generation,

the aforementioned polyurethane raw material comprises hydrophobic silica, which is a foam retaining agent for retaining foam, and light calcium carbonate,

in the polyurethane raw material, the light calcium carbonate is 10 parts by weight or more and 180 parts by weight or less and the hydrophobic silica is 0.6 parts by weight or more with respect to 100 parts by weight of the polyol component.

[ feature 2]

The polyurethane foam according to feature 1, wherein the hydrophobic silica is a silica surface-treated with silicone oil.

[ feature 3]

The polyurethane foam according to feature 1 or 2, wherein the hydrophobic silica has a methanol wettability of 40% or more or a DBA adsorption amount of 60 mmol/kg or less.

[ feature 4]

A polyurethane foam according to any one of features 1 to 3, wherein the light calcium carbonate is not more than 140 parts by weight and the hydrophobic silica is not less than 0.8 parts by weight and not more than 5 parts by weight based on 100 parts by weight of the polyol component in the polyurethane raw material.

[ feature 5]

The polyurethane foam as recited in any one of features 1 to 4, wherein the polyurethane foam has an apparent density of 280kg/m³The following.

[ feature 6]

A polyurethane foam as set forth in any of features 1-5 wherein the polyurethane foam has an impact absorbability as follows: when the polyurethane foam is made into a sheet shape with a thickness of 20mm and impact energy of 50J is vertically applied to the front surface side thereof, the impact force transmitted to the back surface side is less than 8 kN.

[ feature 7]

A process for producing a polyurethane foam according to any one of the features 1 to 6, wherein,

The polyurethane foam according to the features 1 to 7 is obtained from a polyurethane raw material containing a polyol component and a polyisocyanate component, and a foaming gas. Since the polyurethane raw material contains light calcium carbonate as a functional filler, the impact absorbability of the polyurethane foam can be improved. Further, since the hydrophobic silica is contained as a foam retaining agent for retaining foam in the polyurethane raw material, when a polyurethane foam is produced by the mechanical foaming method, the foam retaining property can be improved, and the foam can be easily formed.

Here, the polyurethane raw material preferably contains 10 parts by weight or more and 140 parts by weight or less of light calcium carbonate and 0.8 parts by weight or more and 5 parts by weight or less of hydrophobic silica with respect to 100 parts by weight of the polyol component (feature 4). When the content of the light calcium carbonate is less than 10 parts by weight or the hydrophobic silica is not contained, the foamability when the polyurethane raw material is mixed with the foaming gas and stirred becomes poor. When the content of the hydrophobic silica exceeds 5 parts by weight, the stirring property is good, but the curability is poor (curing is insufficient), and the appearance after molding may be poor. In addition, when the content of the light calcium carbonate is more than 140 parts by weight, the impact absorbability may be lowered. This is considered to be caused by a slight deterioration in foam retentivity when the amount of precipitated calcium carbonate compounded is large. When the amount of light calcium carbonate is 200 parts by weight or more, the raw material becomes a paste, and stirring becomes difficult.

Regarding the impact absorbability of the polyurethane foam, it is preferable that the impact force transmitted to the back surface side is less than 8kN when the polyurethane foam is made into a sheet shape having a thickness of 20mm and 50J of impact energy is perpendicularly applied to the front surface side thereof (feature 6). The polyurethane foam having such an impact absorbability can be used for a protector of CE marking standards, for example.

Further, as for the hardness of the polyurethane foam, 25% compression hardness of less than 0.08MPa is preferable. When the polyurethane foam having such hardness is used for an insole or a protector, a good fitting feeling can be given to a user.

While the present invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.

It is to be noted that the present application is based on japanese patent application filed on 11/15/2018 (japanese patent application 2018-. In addition, all references cited herein are incorporated by reference in their entirety.

Description of the symbols

20 hydrophobic silica

21 matrix silica

Claims

1. A polyurethane foam obtained from a polyurethane raw material containing a polyol component and a polyisocyanate component and a gas for foam generation,

the polyurethane raw material comprises hydrophobic silica and light calcium carbonate, the hydrophobic silica is used as a foam retaining agent for retaining foam,

2. The polyurethane foam according to claim 1, wherein the hydrophobic silica is a silica surface-treated with silicone oil.

3. A polyurethane foam according to claim 1 or 2, wherein the hydrophobic silica has a methanol wettability of 40% or more or a DBA adsorption amount of 60 mmol/kg or less.

4. A polyurethane foam according to any one of claims 1 to 3, wherein the light calcium carbonate is 140 parts by weight or less and the hydrophobic silica is 0.8 parts by weight or more and 5 parts by weight or less, relative to 100 parts by weight of the polyol component, in the polyurethane raw material.

5. A polyurethane foam as set forth in any one of claims 1-4 wherein the polyurethane foam has an apparent density of 280kg/m³The following.

6. A polyurethane foam as set forth in any one of claims 1-5 wherein the polyurethane foam has an impact absorbency as follows: when the polyurethane foam is made into a sheet shape with a thickness of 20mm and impact energy of 50J is vertically applied to the front surface side thereof, the impact force transmitted to the back surface side is less than 8 kN.

7. A process for producing a polyurethane foam according to any one of claims 1 to 6, wherein,