COMPOSITION FOR FORMING RIGID POLYURETHANE FOAM HAVING AIR PERMEABILITY AND RIGID POLYURETHANE FOAM

Technical Field [0001]

The present invention relates to a composition for forming a rigid polyurethane foam having air permeability, and a rigid polyurethane foam which is a molded product of the composition.

Background Art [0002]

Polyurethane foams are roughly divided into flexible polyurethane foams and rigid polyurethane foams. The flexible polyurethane foam is a soft and resilient polyurethane foam having a cell structure of open cells, and has excellent shock absorption. In addition, the flexible polyurethane foam has high air permeability and has sound absorption properties due to its cell structure. On the other hand, a rigid polyurethane foam is a polyurethane foam having a cell structure of closed cells and excellent thermal insulation performance.

[0003]

The flexible polyurethane foams and the rigid polyurethane foams had different properties and applications due to difference in their cell structures, but among the rigid polyurethane foams, particularly, as a rigid polyisocyanurate foam, one having a cell structure of closed cells and having properties as a shock absorbing foam has also been proposed. However, with regard to the sound absorption properties, it is important to improve air permeability by the cell structure of open cells. There was still a room for improvement in obtaining a rigid polyurethane foam having air permeability (Patent Literature 1 to 5). Citation List Patent Literatures [0004]

Patent Literature 1: JP 2018-522100 A Patent Literature 2: JP 2011-529983 A

Patent Literature 3: JP H10-36475 A Patent Literature 4: JP 2012-520915 A Patent Literature 5: JP HI 1-181045 A Summary of Invention Technical Problem [0005]

Accordingly, an object of the present invention is to provide a composition for forming a rigid polyurethane foam having air permeability, in order to solve the problems of conventional technologies described above. Also, another object of the present invention is to provide a rigid polyurethane foam having air permeability, formed from the composition.

Solution to Problem [0006] The present inventor has conducted intensive studies and consequently found that cells were broken by using a water-insoluble oil having no hydrophilic group in its molecule, for example, at least one oil selected from the group consisting of silicone oil, machine oil, fuel oil, cutting oil and insulating oil, in formulation of the rigid polyurethane foam, and a rigid polyurethane foam having air permeability was obtained, thereby completing the present invention. [0007]

The present inventor has further studied to improve compressive strength of the rigid polyurethane foam, and found that, by containing a certain amount of sugar-based polyol in a polyol component, a rigid urethane foam more excellent in balance between air permeability and compressive strength can be formed while maintaining excellent air permeability.

[0008]

That is, the composition for forming a rigid polyurethane foam of the present invention contains a polyol component, a polyisocyanate component, and a water-insoluble oil having no hydrophilic group in its molecule. The composition preferably further contains a foaming agent selected from the group consisting of physical foaming agents, water and combinations thereof, and the content of the water-insoluble oil is 0.01% to 1.0% by mass based on the composition.

[0009]

In a preferred embodiment of the composition for forming a rigid polyurethane foam of the present invention, the polyol component contains a sugar-based polyol in an amount of 60% by mass or less based on the polyol component.

[0010]

In another preferred embodiment of the composition for forming a rigid polyurethane foam of the present invention, the sugar-based polyol has afunctional group number of 4 to 8.

[0011]

In another preferred embodiment of the composition for forming a rigid polyurethane foam of the present invention, the polyol component contains a polyol based on a polyhydric alcohol having a functional group number of 5 to 6 in an amount of 60% by mass or less based on the polyol component.

[0012]

Moreover, the rigid polyurethane foam of the present invention is characterized by being formed from the composition for forming a rigid polyurethane foam.

Advantageous Effects of Invention

[0013]

According to the composition for forming a rigid polyurethane foam of the present invention, it is possible to provide a composition which can form a rigid polyurethane foam excellent in air permeability, and preferably having a good balance between air permeability and compressive strength. Further, according to the rigid polyurethane foam of the present invention, it is possible to provide a rigid polyurethane foam formed from the composition excellent in air permeability, and preferably having a good balance between air permeability and compressive strength.

Description of Embodiments [0014]

Hereinafter, the composition for forming a rigid polyurethane foam of the present invention (hereinafter, also simply referred to as “the composition of the present invention”) will be described in detail. The composition of the present invention is a composition containing a polyol component, a polyisocyanate component, a water-insoluble oil having no hydrophilic group in its molecule, and a crosslinking agent, a catalyst, a foaming agent, and the like, as necessary, and is a composition used for forming a rigid polyurethane foam. In addition, the composition of the present invention can also be referred to as a raw material composition for a rigid polyurethane foam.

[0015]

The polyol component used in the composition of the present invention is a compound having a plurality of hydroxyl groups and is preferably a polymer polyol. Specific examples thereof include polyether polyol, polyester polyol, polycarbonate polyol, polyester ether polyol, polyester polycarbonate polyol, polylactone polyol, polybutadiene polyol, polymer polyol, silicone polyol, and the like. These polyol components may be used alone or in combination of two or more. The polyol component is particularly preferably chosen from polyether polyols, polyester polyols, polycarbonate polyols, polyester ether polyols, polyester polycarbonate polyols and combinations of two or more thereof. The polyol component is most preferably chosen from polyether polyols, polyester polyols, polycarbonate polyols, polyester ether polyols, polyester polycarbonate polyols and combinations of two or more of said polyols, wherein said polyether polyols are aliphatic polyether polyols and/or wherein said polyol component does not contain any benzylic ethers. [0016]

Among the polyol components, examples of the polyether polyol include polyadducts of cyclic ether, condensates of polyhydric alcohols, and the like. Here, examples of the cyclic ether include styrene oxide, ethylene oxide, propylene oxide, tetrahydrofuran, butylene oxide, epichlorohydrin, and the like. These cyclic ethers may be used alone or in combination. Also, examples of the polyhydric alcohol include diols such as ethanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,6- hexanediol, 2,2-dimethyl- 1,3-propanediol, 1,4-dihydroxy cyclohexane, 1,4-dimethylolcyclohexane, 1,8-octanediol, 1,10-decanediol and 1,12-dodecanediol, polyhydric alcohols having a functional group number of 3 such as trimethylolpropane and glycerol, polyhydric alcohols or amines having a functional group number of 4 such as pentaerythritol and ethylenediamine, amines having a functional group number of 5 such as diethylenetriamine, polyhydric alcohols having a functional group number of 6 such as sorbitol, and polyhydric alcohols having a functional group number of 8 such as sucrose. These polyhydric alcohols may be used alone or in combination. For example, a polyadduct of tetrahydrofuran is known as polytetramethylene ether glycol (PTMG).

[0017]

The polyester polyol can be produced by adjusting production conditions of polyester, and examples thereof include polyesters having hydroxyl groups at both ends of the main chain, and more specifically, linear polyester polyols, slightly branched polyester polyols, and the like. The polyester polyols can be prepared by known methods using aliphatic, cycloaliphatic or aromatic dicarboxylic acids, a diol, and optionally polycarboxylic acids and/or a trifunctional or higher functional polyol. [0018]

The polylactone polyols are homopolymers or copolymers of lactones such as e- caprolactone, b-butyrolactone, g-butyrolactone, g-valerolactone, and d-valerolactone, and examples thereof include polylactones having hydroxyl groups at both ends of the main chain, and the like.

[0019] The polycarbonate polyol can be produced by adjusting production conditions of polycarbonate, and examples thereof include polycarbonates having hydroxyl groups at both ends of the main chain, and the like. Moreover, examples of the polybutadiene polyol include polybutadiene having hydroxyl groups at both ends of the main chain, and the like. Examples of the polymer polyol include those obtained by polymerizing vinyl monomers such as acrylonitrile and styrene in a polyether polymer, and the like. Examples of the silicone polyol include polysiloxane having hydroxyl groups at both ends of the main chain, and the like.

[0020]

The polyol component preferably has a hydroxyl value of 30 to 700 mgKOH/g, and further preferably 35 to 630 mgKOH/g. The hydroxyl value is the number of mg of potassium hydroxide required to neutralize free hydroxyl groups in 1 g of a sample after complete acetylation with acetic anhydride (see JIS K 15572007).

[0021]

The polyol component preferably has a functional group number (fn) of 3 to 6 and further preferably 3 to 5, and the functional group number (fn) per polyol molecule is determined from the hydroxyl value (OHV) of the polyol and the number average molecular weight (Mn) by the following calculation formula. n = Mn (g/mol) x OHV (mgKOH/g)/56110

[0022]

In the composition of the present invention, the content of the polyol component is appropriately adjusted according to the amount of the poly isocyanate component, as described later, and it can be exemplified as 10 to 50% by mass and is preferably 15 to 40% by mass.

[0023]

The polyol component used in the composition of the present invention preferably contains a sugar-based polyol, more preferably contains the sugar-based polyol in an amount of 60% by mass or less and further preferably contains the sugar-based polyol in an amount of 40% by weight or less based on the polyol component, and more preferably contains the sugar-based polyol in an amount of 10% by mass or more and further preferably contains the sugar-based polyol in an amount of 20% by mass or more based on the polyol component. By containing a certain amount of the sugar-based polyol in the polyol component, a rigid urethane foam having a good balance between air permeability and compressive strength can be formed.

The sugar-based polyol in the present invention is a polyether polyol obtained by addition polymerization of one or more of ethylene oxide, propylene oxide, butylene oxide and the like using a saccharide having a functional group number of 4 to 8, for example, a polyhydric alcohol such as sucrose, as an initiator.

In addition, sugar-based polyols generally have a high viscosity, and thus include those to which glycol or the like is added for viscosity adjustment.

[0024]

The sugar-based polyol preferably has a hydroxyl value of 200 to 500 mgKOH/g, and further preferably 300 to 460 mgKOH/g.

[0025]

The polyol component used in the composition of the present invention preferably contains a polyol based on a polyhydric alcohol having a functional group number of 5 to 6, like a sugar alcohol such as sorbitol, more preferably contains the polyhydric alcohol in an amount of 60% by mass or less and further preferably contains the polyhydric alcohol in an amount of 40% by mass or less based on the polyol component, and more preferably contains the polyhydric alcohol in an amount of 10% by mass or more and further preferably contains the polyhydric alcohol in an amount of 20% by mass or more based on the polyol component. Polyols based on polyhydric alcohols having a functional group number of 5 to 6, like sugar alcohols such as sorbitol, particularly preferably polyether polyols containing sorbitol as a polyhydric alcohol, can improve the balance between air permeability and compressive strength, like sugar-based polyols.

[0026]

The polyol based on a polyhydric alcohol having a functional group number of 5 to 6 preferably has a hydroxyl value of 100 to 600 mgKOH/g, and further preferably 200 to 500 mgKOH/g.

[0027]

The sugar-based polyol has a functional group number (fn) of preferably 4 to 8, and further preferably 4.5 to 6.5.

[0028]

The polyisocyanate component used in the composition of the present invention is a compound having a plurality of isocyanate groups. Examples thereof include aliphatic, alicyclic, aromatic or araliphatic polyisocyanates, and modified products of these polyisocyanates are also included. Examples of the modified polyisocyanate include polyisocyanates having a structure such as uretdione, isocyanurate, urethane, urea, allophanate, biuret, carbodiimide, iminooxadiazinedione, oxadiazinetrione, or oxazolidone. Further, as the polyisocyanate component, an isocyanate group- containing prepolymer obtained by reacting a polyol with a polyisocyanate may be used.

[0029]

Among the above polyisocyanate components, the aliphatic polyisocyanate is preferably an aliphatic diisocyanate having 2 to 18 carbon atoms, and specific examples include 1,6- hexamethylene diisocyanate, lysine diisocyanate, and the like. The alicyclic polyisocyanate is preferably an alicyclic diisocyanate having 4 to 16 carbon atoms, and specific examples include isophorone diisocyanate (IPDI), 4,4’-dicyclohexylmethane diisocyanate, norbornane diisocyanate, and the like. Examples of the aromatic polyisocyanate include 1,3-and/or 1,4-phenylene diisocyanate, 2,4-and/or 2,6-tolylene diisocyanate (TDI), polymeric TDI (also referred to as crude TDI or crude TDI), 2,4’ -and/or 4,4’-diphenylmethane diisocyanate (MDI), polymethylene polyphenyl isocyanate (also referred to as crude MDI or polymeric MDI), polyaryl polyisocyanate (PAPI), and the like. These polyisocyanate components may be used alone or in combination of two or more.

[0030]

The polyisocyanate component preferably has an isocyanate group content of 20 to 40% by mass, and further preferably 25 to 35% by mass. In the present specification, the isocyanate group content is determined according to JIS K 1603. [0031]

In the composition of the present invention, the content of the polyisocyanate component is preferably an amount such that the isocyanate index is 80 to 500, further preferably 100 to 250, and still more preferably 150 to 250. In the present specification, the isocyanate index refers to a value obtained by multiplying 100 by the ratio of the isocyanate group of the polyisocyanate component to the total active hydrogen that reacts with isocyanate groups of the polyol component, a foaming agent (carboxylic acid or water) and the like.

The composition of the present invention can be a composition used for forming polyisocyanurate, and can also be referred to as a raw material composition for a polyisocyanurate foam.

The polyisocyanurate foam is a resin-based foam obtained from a polyol and a polyisocyanate similarly to the polyurethane foam, and contains a polymer having a urethane bond. On the other hand, the polyisocyanurate foams are distinguished from the polyurethane foams because they contain isocyanurate ring structures in a certain proportion or more. The isocyanurate ring formed by the isocyanate trimerization reaction is bonded to the polymer having a urethane bond, but a part of which may be present in the polyisocyanurate foam, as a trimer itself that is not bonded to the polymer having a urethane bond. While the resin constituting the polyurethane foam is referred to as a urethane resin, the resin constituting the polyisocyanurate foam is also referred to as a polyisocyanurate resin.

In the present specification, the polyisocyanurate foam refers to one having an isocyanate index of 150 or more and using a trimerization catalyst.

[0032]

The composition of the present invention contains a water-insoluble oil having no hydrophilic group in its molecule. By using the oil for the rigid polyurethane foam, air permeability can be improved.

Here, the hydrophilic group includes a hydrophilic group that does not cause a surfactant effect, and examples thereof include a hydroxyl group, a carbonyl group, an aldehyde group, a carboxyl group, an ether group (excluding polysiloxane), an ester group, an amino group, a nitro group, a nitrile group, acid anhydrides, and the like.

The term “water-insoluble” means a highly hydrophobic property that separates to form an aqueous layer and an oil layer when mixed with water.

The water-insoluble oil having no hydrophilic group in its molecule has a low surface tension and is uniformly diffused into a foaming liquid, so that the oil easily contacts the surface of the foam. In addition, it is considered that since these oils have low solubility in the polyol component, isocyanate component, and water, the surface tension of the surface of the foam in contact with the oil locally decreases, and this portion is pulled by a portion with a large surface tension which does not touch the oil to break the foam and a foam having air permeability can be formed.

When the oil is dissolved in the liquid forming the foam (polyol component, isocyanate component, water), it is considered that the surface tension of the liquid becomes uniform, and foaming is improved to stabilize the foam, so that the effect of the present invention is not obtained, that is, it is desirable that the oil of the present invention has no surfactant effect.

Further, the surface tension of the oil of the present invention is preferably low, and is preferably 35 mN/m or less.

[0033]

The composition of the present invention can contain at least one oil selected from the group consisting of silicone oil, machine oil, fuel oil, cutting oil, and insulating oil.

The silicone oil is a colorless and transparent liquid, having a linear structure and exhibiting oil-like properties. It is chemically stable and also has little change in viscosity with temperature.

[0034]

The machine oil is lubricating oil, grease or the like, and specific examples thereof include vacuum pump oil, hydraulic oil, turbine oil, compressor oil, gear oil, sliding surface oil, bearing oil, calibration oil, machine tool oil, compressor oil, and the like. [0035]

The cutting oil is preferably oil-based cutting oil, and specifically includes those specified in JIS K2241-2000. The insulating oil includes an insulating oil specified in JIS C 2320.

[0036]

Any of the above oils can be used as oil in the composition of the present invention even if they are deteriorated as a result of being used for those applications and become a so-called waste oil.

As the oil of the present invention, a silicone oil composed of polydimethylsiloxane is preferable, or a mineral oil composed of petroleum hydrocarbon is preferable.

[0037]

In the composition of the present invention, the content of the oil is preferably 0.01 to 1.0% by mass.

[0038]

The composition of the present invention preferably contains a foaming agent, more preferably a foaming agent selected from the group consisting of physical foaming agents, water and combinations thereof. Foaming agents are generally classified into physical foaming agents and chemical foaming agents. Specific examples of the physical foaming agent include fluorocarbons such as chlorofluorocarbons (CFC), hydrochlorofluorocarbons (HCFC) and hydrofluorocarbons (HFC), hydrocarbons such as hydrofluoroolefins (HFO), heptane, hexane and pentane, carbon dioxide, and the like. On the other hand, examples of chemical foaming agents include water, carboxylic acids such as formic acid, acetic acid, glutaric acid and succinic acid, and the like. The foaming agents of the present invention may be used alone or in combination of two or more, and a physical foaming agent and water may be used in combination, preferably a physical foaming agent and water may be used in combination. In the polyurethane foam composition, the content of the foaming agent is, for example, 1 to 20% by mass. The foaming agent used in the composition of the present invention is preferably water.

[0039] The composition of the present invention preferably contains a catalyst. Examples of the catalyst include foaming catalysts that promote a reaction between water and isocyanate, catalysts (resinification catalysts) that promote a reaction between polyol and isocyanate, catalysts (trimerization catalysts) that promote a trimerization reaction of isocyanate (that is, formation of an isocyanurate ring), and the like.

[0040]

Examples of the foaming catalyst include dimorpholine-2, 2-diethyl ether, N,N,N',N",N"- pentamethyldiethylenetriamine, bis(dimethylaminoethyl)ether, 2-(2-dimethylaminoethoxy)ethanol, and the like.

Examples of the resinification catalyst include amine catalysts such as triethylenediamine, N,N-dimethylcyclohexylamine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N",N"',N"'- hexamethyltriethylenetetramine, N-dimethylaminoethyl-N'-methylpiperazine, N,N,N',N'- tetramethylhexamethylenediamine, 1,2-dimethylimidazole, N,N-dimethylaminopropylamine and bis(dimethylaminopropyl)amine, alkanolamine catalysts such as N,N-dimethylaminoethanol, N,N,N'-trimethylaminoethylethanolamine, N,N,N'-trimethyl-N'-hydroxyethyl bisaminoethyl ether, N-(3-dimethylaminopropyl)-N,N-diisopropanolamine, N-(2-hydroxyethyl)-N'-methylpiperazine, N,N-dimethylaminohexanol and 5-dimethylamino-3-methyl-l-pentanol, and the like.

Examples of the trimerization catalyst include aromatic compounds such as 2,4,6- tris(dialkylaminoalkyl)hexahydro-S-triazine, l,3,5-tris(N,N-dimethylaminopropyl)hexahydro-S- triazine, 2,4,6-tris(dimethylaminomethyl)phenol, 2,4-bis(dimethylaminomethyl)phenol and 1- isobutyl-2-methylimidazole, alkali metal carboxylates such as potassium acetate, potassium 2- ethylhexanoate and potassium octylate, quaternary ammonium salts of carboxylic acid, or other onium salts, and the like.

[0041]

In addition, the catalysts may be used alone or in combination of two or more. In the polyurethane foam composition, the content of the catalyst is appropriately adjusted depending on reactivity of the polyurethane foam composition, and is, for example, 0.1 to 1% by mass. [0042]

The composition of the present invention preferably contains a crosslinking agent. Examples of the crosslinking agent include polyhydric alcohols such as 1,4-butanediol, ethylene glycol, diethylene glycol and glycerin, and amines such as ethanolamines and polyethylene polyamines. The content of the crosslinking agent is preferably 0.5 to 5.0% by mass.

[0043]

In the composition of the present invention, as other components, various pigments and coloring agents, a filler, an antioxidant, an ultraviolet absorber, a heat stabilizer, a light stabilizer, a plasticizer, a fungicide, an antibacterial agent, an industrial cashew nut shell liquid, a solvent, a viscosity-reducing agent, a depressurizing agent, a flame retardant, a foam stabilizer and the like may be appropriately blended as necessary. For these components, commercial items can be suitably used. [0044]

The composition of the present invention can be prepared by mixing various components appropriately selected as necessary. For example, the composition of the present invention can be prepared by mixing a polyol mixture containing a polyol component, a crosslinking agent, a catalyst, a foaming agent, oil and the like with a polyisocyanate component. In preparing the composition of the present invention, the polyisocyanate component may be used alone or in a mixture with other components.

[0045] The foaming method of the rigid polyurethane foam of the present invention is not particularly limited, and known foaming means, for example, hand mixing foaming, simple foaming, injection method, floss injection method, spray method, and the like can be used. Also, the molding method of the polyisocyanurate foam is not particularly limited, and known molding means, for example, mold molding, slab molding, laminate molding, in-situ foam molding, and the like can be used.

[0046]

The rigid polyurethane foam of the present invention can be used for various applications such as ships, vehicles, plants, heat insulation equipment, architecture, civil engineering, furniture, and interiors, and can be suitably used as an interior part of an automobile, particularly, a shock absorbing member having air permeability, since it has excellent air permeability.

[0047]

The rigid polyurethane foam of the present invention preferably has a density of 20 to 120 kg/m ³ , and further preferably 25 to 80 kg/m ³ . In the present specification, the density of the rigid urethane foam is measured according to JIS K 7222: 1999.

There is a correlation between the density and compressive strength, and the higher the density, the higher the compressive strength. In the case of a shock absorbing foam, required compressive strength differs depending on use site, and can be dealt with by changing the density. [0048]

The rigid polyurethane foam of the present invention has an air permeability of preferably 0.01 to 3.00 L/s, and further preferably 0.1 L/s or more. In the present specification, the air permeability of the rigid urethane foam is measured according to JIS K6400-7A method (negative pressure type).

Generally, the better the air permeability, the better the sound absorption properties, and when there is no air permeability, no sound is absorbed.

The mechanism of sound absorption is that when sound is applied to urethane foam made of a porous material by air propagation, sound vibration is transmitted to bubbles inside the urethane material, and a viscous friction phenomenon of air occurs due to the vibration of the transmitted sound inside the bubbles to convert the energy of the incident sound into heat energy, thereby generating a sound absorbing effect.

[0049]

The rigid polyurethane foam of the present invention preferably has a compressive strength of 150 to 1200 N, and further preferably 200 N or more. In the present specification, the compressive strength of the rigid urethane foam is measured according to JIS K 6400-7: 2012.

[0050] The rigid urethane foam of the present invention has a sound absorption coefficient of preferably 30% or more, and further preferably 40% or more as an average value at a frequency of 800 Hz to 4000 Hz. In the present specification, the sound absorption properties of the rigid urethane foam are measured using a normal incident sound absorption coefficient measurement system (Win

ZacMTX) manufactured by Nihon Onkyo Engineering Co., Ltd.

Examples

[0051]

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the present invention is not limited to the following Examples. [0052]

1. Materials

1) Polyol Component

Polyol 1: Sumiphen 3900 (manufactured by Sumika Covestro Urethane Co., Ltd.), a polyether polyol obtained by adding propylene oxide and ethylene oxide to glycerin, having a functional group number fn = 3, a hydroxyl value of 35 mgKOH/g, and an average molecular weight of about 5,000;

Polyol 2: Sumiphen VB (manufactured by Sumika Covestro Urethane Co., Ltd.), a polyether polyol obtained by adding propylene oxide to ethylenediamine, having a functional group number fn = 4.0, a hydroxyl value of 630 mgKOH/g, and an average molecular weight of about 360; Polyol 3: Sumiphen TS (manufactured by Sumika Covestro Urethane Co., Ltd.), a polyether polyol obtained by adding propylene oxide to sucrose, having a functional group number fn = 5.8, a hydroxyl value of 380 mgKOH/g, and an average molecular weight of about 880;

Polyol 4: J406 (manufactured by Sumika Covestro Urethane Co., Ltd.), a polyether polyol obtained by adding propylene oxide to sorbitol, having a functional group number fn = 6.0, a hydroxyl value of 430 mgKOH/g, and an average molecular weight of about 780

2) Polyisocyanate component

Polymeric MDI: Sumidur 44V20 L (manufactured by Sumika Covestro Urethane Co., Ltd.), an isocyanate group content of 31.5% by mass

3) Crosslinking agent Ethylene glycol

4) Catalyst

Catalyst 1: KAOLIZERNo. 3 (manufactured by Kao Corporation); Catalyst 2: DABCO K-15 (manufactured by Evonik Japan Co., Ltd., 70% diethylene glycol solution of potassium 2-ethylhexanoate);

5) Foaming agent

Water

6) Oil

Silicone oil: SH200 (manufactured by Dow Coming Toray Co., Ltd) dimethylsiloxane (surface tension: 26 mN/m);

Vacuum pump oil: Fairback White (manufactured by ENEOS) 100% petroleum hydrocarbon mineral oil (surface tension: 32 mN/m);

Used oil for vacuum pump oil: the above vacuum pump oil that was used under the conditions of an operating temperature of 60°C to 150°C and a use period of about two and half years at a mold temperature controller (model MC5-G3-55) manufactured by MATSUI MFG. CO., LTD., which had a light brown transparent appearance before use, but turned dark brown after use [0053]

2. Method

Preparation of Polyol Mixture>

1) In order to prepare a polyol mixture having a formulation shown in Table 1, a polyol component, a crosslinking agent, a catalyst and oil are charged and mixed in a mixing pot.

2) The mixture is stirred for 5 minutes or more, and it is visually confirmed that the mixture has been sufficiently stirred.

3) A foaming agent is added to the resulting mixture and the mixture is sufficiently mixed to prepare a polyol mixture.

[0054]

Production and Evaluation of Rigid Urethane Foam>

4) Production of rigid urethane foam is performed by hand mixing foaming. Specifically, a polyisocyanate component adjusted to 20°C is added to a polyol mixture adjusted to 20°C at a mixing mass ratio shown in Table 1, and after stirring and mixing, the mixture is poured into a 1 -liter cup while being in a liquid state, and foamed and cured.

5) After the rigid urethane foam was cured, a cube (dimensions: length (5 cm), width (5 cm), height (2 to 3 cm)) sample was cut out, and free core density, air permeability, compressive strength and sound absorption coefficient were measured. Measuring methods and equipment used are as described above.

[0055]

(Examples 1 to 7 and Comparative Example 1)

The rigid polyurethane foams of Comparative Example 1 and Examples 1 to 7 were prepared according to the description of the above “2. Method”, and the quality was evaluated. The results are shown in Table 1 (unless otherwise specified, the numerical values of each component in the table represent their parts by mass).

A time when a foaming reaction started was described as cream time (CT), a time when the height of the foam reached the highest point was described as rise time (RT), and a time when the foam surface was cured and “tackiness” disappeared was described as tack-free time (TFT). It is desirable that the free core density is 20 kg/m3 to 120 kg/m3, the air permeability is

0.1 (L/s) or more, the compressive strength is 150 N to 1200 N, and the sound absorption coefficient is 30% or more as an average value at 800 Hz to 4000 Hz.

[0056]

[Table 1]

[0057]

From Table 1, it can be seen that the rigid urethane foams of Examples have more air permeability and better sound absorption properties than Comparative Example. It can also be seen that the compressive strength is maintained.