JP2003277462A - Method for producing rigid polyurethane foam - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a rigid polyurethane foam having such good surface appearance as to be suppressed in void development despite using a low-boiling foaming agent. <P>SOLUTION: The method for producing the rigid polyurethane foam comprises carrying out a reaction between a polyol compound and an isocyanate compound in the presence of the foaming agent, a foam stabilizer and a catalyst. In this method, an organic compound ≤20°C in boiling point is used as at least part of the foaming agent. As the polyol compound, a polyol mixture containing 0.5-30 mass% of a polyol(A) is used, wherein the polyol(A) is a polyoxyalkylene polyol <200 mgKOH/g in hydroxy number containing 5-40 mass% of oxyethylene groups based on the whole polyol (A). <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing rigid polyurethane foam (hereinafter referred to as rigid foam), and more particularly to a method for improving the appearance of foam when a low boiling point blowing agent is used.

[0002]

2. Description of the Related Art As a method for producing a rigid foam molding covered with a face material, a production method of injecting a foaming concentrate composition from a foaming machine between the face materials is usually adopted. As the foaming machine, a high-pressure foaming machine for collision-mixing a foaming stock solution composition at a high pressure or a low-pressure foaming machine for mixing a foaming stock solution composition at a relatively low pressure through a mixer is used. The injected undiluted composition foams while polymerizing, fills the space between the face materials, and cures to self-adhere to the face material to form a structure having heat insulating properties.

As one of methods for producing rigid foam (foaming method), there is a foaming method in which a foaming agent having a boiling point near room temperature and a foaming agent having a gas (that is, low boiling point) at room temperature are used in combination. Is generally called floss foaming. The advantages of floss foaming are that the filling property after injection is good, and that the pressure during foaming is low and large-scale mold clamping equipment is not required. In this way, proposals have been made regarding the production of rigid foams using a low-boiling point blowing agent (see, for example, Patent Documents 1 to 3).

[0004]

[Patent Document 1] JP-A-2-235982

[Patent Document 2] Japanese Unexamined Patent Publication No. 5-239251

[Patent Document 3] Japanese Patent Application Laid-Open No. 3-7738

[0005]

However, in this froth foaming, the use of this low boiling point blowing agent poses a problem of generation of voids (also referred to as froth voids). Particularly in recent years, since the face material tends to be thinned for cost reduction and weight reduction, there is a problem that even slight irregularities of the rigid foam appear on the surface of the face material and impair the appearance. Further, since the void portion has a weak adhesive force between the foam and the face material, there is a problem that the face material and the foam are separated from the void when the vibration or stress is applied.

Further, it has been proposed to use a fluorinated hydrocarbon (hereinafter referred to as HFC) or a hydrocarbon as a foaming agent having no fear of depleting the ozone layer. HFC
Is 1,1,1,2-tetrafluoroethane (boiling point: −26 ° C.) (hereinafter referred to as HFC-134a),
1,1,1,3,3-pentafluoropropane (boiling point:
15 ° C.) (hereinafter referred to as HFC-245fa) and 1,1,1,3,3-pentafluorobutane (boiling point: 4
0 ° C.) (hereinafter referred to as HFC-365mfc) and the like, and as the hydrocarbon, cyclopentane (boiling point: 49
C.), hexane (boiling point: 69.degree. C.), cyclohexane (boiling point: 80.degree. C.). Of these, HFC-134
When a compound that is a gas at room temperature, such as a or HFC-245fa, is used as a foaming agent for rigid foams, froth voids are likely to occur. Furthermore, the foam tends to break more easily in the foaming process than the conventional foaming agents, and has many voids and tends to become large.

[0007] Patent Document 1 proposes to use HFC-245fa as a foaming agent for producing a polyurethane foam. Further, in Patent Document 2, HF
A method for producing a rigid foam using C-245fa and water together has been proposed. Further, in Patent Document 3, HFC-13
It has been proposed to use 4a as a blowing agent. However, these proposals do not mention the improvement of floss voids.

The present invention solves the above-mentioned problems and provides a method for producing a rigid foam having a good appearance without fear of destruction of the ozone layer.

[0009]

That is, the present invention provides a method for producing a rigid polyurethane foam by reacting a polyol compound and an isocyanate compound in the presence of a foaming agent, a foam stabilizer and a catalyst. An organic compound having a boiling point of 20 ° C. or less is used as a part, and the following polyol (A) is used as a polyol compound in an amount of 0.5 to 3
A method for producing a rigid polyurethane foam, which comprises using a polyol mixture containing 0% by mass. However, the polyol (A) has a hydroxyl value of 200 mgKOH
/ G and the oxyethylene group is a polyol (A)
It is a polyoxyalkylene polyol containing 5 to 40% by mass relative to the whole.

The present invention improves the compatibility of the polyol compound and the foaming agent and the compatibility of the polyol compound and the isocyanate compound to prevent the generation of froth voids due to the low boiling point foaming agent. . That is, by using a specific long-chain polyoxyalkylene polyol, it is possible to improve the compatibility of each raw material composition and improve the stability of foam during the foaming process.

The boiling point used as the foaming agent is 20.
It is preferable that the organic compound having a temperature of 0 ° C. or lower contains 1,1,1,3,3-pentafluoropropane and / or 1,1,1,2-tetrafluoroethane. In particular, a fluorinated hydrocarbon mixture composed of 1,1,1,3,3-pentafluoropropane and 1,1,1,2-tetrafluoroethane as an organic compound having a boiling point of 20 ° C. or lower used as the foaming agent. And the proportion of 1,1,1,3,3-pentafluoropropane in the fluorinated hydrocarbon mixture is preferably 1 to 99% by mass.

As the foam stabilizer, it is preferable to use the following foam stabilizer (F) in an amount of 0.1 to 5 parts by mass based on 100 parts by mass of the entire polyol compound. However, the foam stabilizer (F) is a silicone-based foam stabilizer obtained by grafting a polyoxyalkylene chain on a polysiloxane chain, and the polysiloxane chain has a chain length of 2000 to 3000. Has a chain length of 1000 to 2000, a graft number of 1.5 to 2.5, does not have a hydroxyl group at the polyoxyalkylene chain terminal, and the ratio of the polysiloxane chain to the entire foam stabilizer is 30 to. The silicone foam stabilizer is 50% by mass.

As the foaming device, it is preferable to use a simple foaming device which operates only by operating the pressure of the gas supplied from the gas cylinder.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION (Polyol) In the present invention, the following polyol (A) is used in an amount of 0.5 to 3 as a polyol compound.
A method for producing a rigid foam is characterized in that a polyol mixture containing 0% by mass is used. However, the polyol (A) is a polyoxyalkylene polyol having a hydroxyl value of less than 200 mgKOH / g and containing oxyethylene groups in an amount of 5 to 40% by mass based on the total amount of the polyol (A).

The hydroxyl value of the polyol (A) is 200.
It is less than mgKOH / g, preferably 170 mgKOH / g or less, more preferably 100 mgKOH / g or less, and particularly preferably 70 mgKOH / g or less. The lower limit of the hydroxyl value is not particularly limited, but is preferably 30 mgKOH / g or more, more preferably 40 mgKOH / g or more, and particularly preferably 50 mgKOH / g or more. When the hydroxyl value is 200 mgKOH / g or more, that is, when the molecular weight is low, it is difficult to improve the compatibility of each raw material composition, which is not preferable.

The polyol (A) is a polyoxyalkylene polyol obtained by ring-opening addition polymerization of alkylene oxide as an initiator. As the initiator, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, tripropylene glycol, glycerin, trimethylolpropane, pentaerythritol, polyhydric alcohols such as sugars; diethanolamine, alkanolamines such as triethanolamine, Alternatively, a small amount of these alkylene oxide adducts may be mentioned.

As the alkylene oxide to be subjected to ring-opening addition polymerization with the above initiator, ethylene oxide and alkylene oxide having 3 or more carbon atoms are used in combination. Examples of the alkylene oxide having 3 or more carbon atoms include propylene oxide,
1,2-epoxybutane, 2,3-epoxybutane, styrene oxide and the like can be mentioned, but propylene oxide is preferable. The ethylene oxide and the alkylene oxide having 3 or more carbon atoms may be sequentially added to the initiator, or a mixture of ethylene oxide and the alkylene oxide having 3 or more carbon atoms may be added. When this mixture is added, a random addition structure is obtained in which ethylene oxide and alkylene oxide having 3 or more carbon atoms are randomly added.

The polyol (A) has an oxyethylene group derived from the above-mentioned ethylene oxide, and the proportion thereof is 5 to 40% by mass based on the whole polyol (A), but 10 to 35% by mass. Is preferable, and 10-20 mass% is more preferable. 5% by mass of oxyethylene group
Even if it is less than 40% by mass, the compatibility of each raw material composition is difficult to improve, which is not preferable.

The number of hydroxyl groups in the polyol (A) is 2 to
8 is preferable and 2.8-5.2 is more preferable. However, the number of hydroxyl groups means the average value of the number of active hydrogens of the initiator. If the number of hydroxyl groups is less than 2, the hardness of the rigid foam tends to be insufficient, and if the number of hydroxyl groups exceeds 8 and the dimensional stability tends to be poor, both are not preferable.

In the present invention, a polyol mixture containing the polyol (A) is used as the polyol compound. The proportion of the polyol (A) is 0.5 to 30% by mass, preferably 1 to 20% by mass, based on the entire polyol mixture. When this mixing ratio is less than 0.5% by mass, the compatibility of each raw material composition is difficult to improve, and when it exceeds 30% by mass, the hardness of the obtained foam tends to be insufficient, and the viscosity of the raw material composition is It becomes high and the moldability is liable to deteriorate, which is not preferable.

In the present invention, as the polyol other than the polyol (A) used as the polyol mixture, a polyol usually used in rigid foams may be used, and an active hydrogen compound other than the polyol may be contained.
Examples of the polyol that is usually used for the rigid foam include polyether polyols (polyoxyalkylene polyols), polyester polyols, polyhydric alcohols, and polyhydric phenols, and one or more of these may be used. It is preferable to adopt. The hydroxyl value of the polyol used for these ordinary rigid foams is preferably 200 to 1000 mgKOH / g,
0 to 800 mgKOH / g is more preferable, and 300 to 6
00 mg KOH / g is particularly preferred.

The polyether polyols, like the polyol (A), are polyoxyalkylene polyols obtained by ring-opening addition polymerization of an alkylene oxide as an initiator, but have a higher hydroxyl value (lower than that of the polyol (A)). Molecular weight). The same initiator as the polyol (A) is adopted as the initiator. As the alkylene oxide, ethylene oxide, propylene oxide, 1,2-
Epoxy butane, 2,3-epoxy butane, styrene oxide and the like can be mentioned, and propylene oxide alone or a combination of ethylene oxide and propylene oxide is preferable. Examples of the polyester polyols include polyhydric alcohol-polyhydric carboxylic acid condensation type polyols and cyclic ester ring-opening polymerization type polyols.

As the polyhydric alcohols, those mentioned as the initiator of the polyol (A) can be adopted.
Examples of the polyhydric phenols include a resole-type initial condensate obtained by condensation-bonding phenols with an excess of formaldehyde in the presence of an alkali catalyst, and a benzylic compound reacted in a non-aqueous system when synthesizing the resole-type initial condensate. Examples thereof include a type initial condensate and a novolak type initial condensate obtained by reacting excess phenols with formaldehyde in the presence of an acid catalyst. The molecular weight of these precondensates is 200
It is preferably about 10,000 to 10,000. In the above, examples of the phenols include phenol, cresol, bisphenol A and resorcinol, and examples of the formaldehydes include formalin and paraformaldehyde.

Examples of active hydrogen compounds other than the above-mentioned polyols include polyamines. A polymer-dispersed polyol containing polymer particles may be used as the polyol compound in the present invention. The polymer-dispersed polyol is a dispersion system in which polymer particles (dispersoids) are stably dispersed in a base polyol (dispersion medium).

(Foaming Agent) In the present invention, an organic compound having a boiling point of 20 ° C. or lower is used as at least a part of the blowing agent. By using the polyol (A), a froth void is suppressed and a rigid foam having a good appearance can be produced even if a foaming agent that is gaseous at room temperature is used. Since a gas blowing agent can be used at room temperature, the filling property is good,
It is preferable in that the foaming pressure can be suppressed low. It is preferable to use a chlorine-free compound as the foaming agent from the viewpoint of protecting the ozone layer. An organic compound having a boiling point higher than 20 ° C may be used in combination as a foaming agent, but it is preferable not to use it in combination. As the foaming agent, in addition to the above compounds, air, nitrogen, an inert gas such as carbon dioxide, or water can be used together, and it is particularly preferable to use water together.

The boiling point used as the foaming agent is 20 ° C. or less
The following HFCs and perfluorinated organic compounds
Compounds and hydrocarbons can be mentioned. These are used in combination
HFC (HFC (1 type or a mixture of 2 or more types
It is preferable to use only For HFC, C
H_TwoF_Two(Boiling point: -52 ° C), CF_ThreeCHF_Two(boiling point:
-49 ° C), CF_ThreeCH_TwoF (HFC-134a, boiling
Point: -27 ° C), CF_ThreeCH_Three(Boiling point: -48 ° C), C
HF_TwoCH_Three(Boiling point: -25 ° C), CF_ThreeCF_TwoCHF
_Two(Boiling point: -16 ° C), CF_ThreeCHFCF_Three(Boiling point:-
15 ° C), CF_ThreeCF_TwoCH_TwoF (boiling point: 1 ° C), CF
_ThreeCHFCHF_Two(Boiling point: 7 ° C), CF_ThreeCH_TwoCF_Three
(Boiling point: -1 ° C), CF_ThreeCF_TwoCH_Three(Boiling point: -18
℃), CF_ThreeCHFCH_TwoF (boiling point: 17 ° C), CF_Three
CH_TwoCHF_Two(HFC-245fa, boiling point: 15
℃), CF_ThreeCHFCH_Three(Boiling point: -1 ° C), CF_ThreeC
H_TwoCH_Three(Boiling point: -13 ° C), CH_ThreeCF_TwoCH
_Three(Boiling point: -1 ° C), CH_ThreeCHFCH _Three(Boiling point: -9
℃), CF_ThreeCF_TwoCF_TwoCH_Three(Boiling point: 15 ° C)
You can CF as a perfluoro compound_Four(Boiling
Point: -128 ° C), C_TwoF₆(Boiling point: -78 ° C), C_Three
F₈(Boiling point: -37 ° C), C_FourF₁₀(Boiling point: -2
℃), C ₆F₆(Perfluorobenzene) (Boiling point: 4
℃). As hydrocarbons, propane (boiling
Point: -42 ° C), butane (boiling point: -1 ° C).
It

The boiling point which may be used together as the foaming agent is 2
Organic compounds higher than 0 ° C include the following HFCs and
Examples thereof include fluoro compounds and hydrocarbons. As HFC
Is CHF_TwoCF_TwoCH_TwoF (boiling point: 25 ° C), CH_Two
FCF_TwoCH_TwoF (boiling point: 36 ° C), CHF_TwoCHFC
H_TwoF (boiling point: 40 ° C), CF_ThreeCH_TwoCH_TwoF (boiling
Point: 29 ° C), CF_ThreeCH_TwoCH_TwoCF_Three(Boiling point: 25
℃), CF_ThreeCHFCF _TwoCH_Three(Boiling point: 25 ° C), C
F_ThreeCH_TwoCF_TwoCH_Three(HFC-365mfc, boiling
Point: 40 ° C), CF_ThreeCHFCHFCF_Three(Boiling point: 25
℃), CF_ThreeCF_TwoCF_TwoCH_TwoF (boiling point: 28 ° C),
CF_ThreeCHFCH_TwoCF_Three(Boiling point: 31 ° C), CH_ThreeC
F_TwoCF_TwoCHF_Two(Boiling point: 32 ° C), CF_ThreeCF_TwoC
HFCHF_Two(Boiling point: 32 ° C), CF_ThreeCF_TwoCH_TwoC
HF_Two(Boiling point: 39 ° C), CF_ThreeCHFCHFCH
_Three(Boiling point: 40 ° C), CF_ThreeCH (CF_Three) CH_Three(Boiling
Point: 22 ° C), CH_ThreeCF (CF_Three) CHF_Two(boiling point:
29 ° C), CH_ThreeCH (CF_Three) CH_TwoF (boiling point: 32
℃), CH_ThreeCH (CF_Three) CHF_Two(Boiling point: 41
℃), CH_TwoFCF (CF_Three) CH_TwoF (boiling point: 48
℃), CH_ThreeCF (CHF_Two) CHF_Two(Boiling point: 49
℃). Further, as the perfluoro compound,
C₅F ₁₂(Boiling point: 30 ° C), C₆F₁₄(Boiling point: 56
℃), C₇F₁₆(Boiling point: 82 ° C), C₅F₁₀(Par
Fluorocyclopentane) (boiling point: 21 ° C), C₆F_1
Two(Perfluorocyclohexane) (boiling point: 51 ° C)
Can be mentioned. As the hydrocarbon, pentane (boiling point:
35 ° C), hexane (boiling point: 69 ° C), cyclopentane
(Boiling point: 49 ° C), cyclohexane (boiling point: 80 ° C)
Can be mentioned.

In the present invention, HFC-245 is used as the foaming agent.
fa and / or HFC-134a is preferable, and it is more preferable to include an HFC mixture composed of HFC-245fa and HFC-134a (hereinafter referred to as a specific HFC mixture), and specific H as a blowing agent other than water.
It is especially preferred to include only the FC mixture. That is,
The ratio of the specific HFC mixture as a foaming agent other than water is 50
Mass% or more is preferable, 80 mass% or more is more preferable, 95 mass% or more is especially preferable, and 100 mass% is the most preferable. HFC-245fa in a specific HFC mixture
1 to 99 mass% is preferable, and the ratio of 1 to 80 mass%
Is more preferable, 5 to 60% by mass is further preferable, and 5
˜45% by mass is particularly preferred.

The amount of the organic compound used as the foaming agent in the present invention is 100 parts by mass of the polyol compound.
5 to 150 parts by mass is preferable, and 20 to 60 parts by mass is more preferable. When water is used as a foaming agent in the present invention, the amount of water used is preferably 0.1 to 5 parts by mass, and more preferably 2 to 4 parts by mass with respect to 100 parts by mass of the polyol compound. The foaming agent is usually used as a mixture with the polyol compound, but in order to reduce froth voids, a part of the foaming agent except water may be added to the isocyanate compound.

(Foam stabilizer) In the present invention, it is preferable to use the following foam stabilizer (F) in an amount of 0.1 to 5 parts by mass based on 100 parts by mass of the entire polyol compound.
However, the foam stabilizer (F) is a silicone-based foam stabilizer having a polysiloxane chain grafted with a polyoxyalkylene chain, and the chain length of the polysiloxane chain is 2000 to 300.
0, and the chain length of the polyoxyalkylene chain is 1000.
To 2000, the number of grafts is 1.5 to 2.5, the polyoxyalkylene chain terminal does not have a hydroxyl group, and the ratio of the polysiloxane chain to the entire foam stabilizer is 30.
The silicone foam stabilizer is ˜50% by mass. The use of the above specific foam stabilizer (F) is preferable because the foam is stabilized in the process of foaming and the generation of froth voids is efficiently suppressed.

The specific foam stabilizer (F) has a polysiloxane chain and a polyoxyalkylene chain. Here, the polysiloxane chain means an organopolysiloxane chain having an organic group in its side chain, and examples thereof include a dimethylsiloxane chain and the like. The polyoxyalkylene chain means a portion to which alkylene oxide is added. Examples of addition of alkylene oxide include block addition in which a single alkylene oxide is added, random addition in which two or more kinds of alkylene oxide are randomly added, and the like.
These additions may be mixed. The structure of this foam stabilizer is a structure in which a polysiloxane chain of the main chain is grafted with a polyoxyalkylene chain as a side chain.

The foam stabilizer (F) has a silicone content of 30 to
It is 50% by mass. Here, the silicone content is the ratio of polysiloxane chains in the foam stabilizer (F), and the rest is polyoxyalkylene chains. Examples of the alkylene oxide include ethylene oxide, propylene oxide,
1,2-epoxy butane, 2,3-epoxy butane and the like can be mentioned. Of these, ethylene oxide alone or a combination of ethylene oxide and propylene oxide is preferable.

The chain length of the polyoxyalkylene chain is 1000 to 2000. However, this chain length is a value corresponding to the molecular weight, and for example, when the polyoxyalkylene chain is composed of only oxypropylene groups and the chain length is 1160, polyoxyalkylene having 20 propylene oxides (molecular weight 58) is added. It means a chain. The polyoxyalkylene chain does not have a hydroxyl group at the end. That is, it is preferable that the terminal is OR (where R is a monovalent organic group). Examples of the monovalent organic group include an alkyl group such as a methyl group, an ethyl group, and an isopropyl group; an aryl group such as a phenyl group; an acyl group such as an acetyl group; among these, an organic group having 1 to 6 carbon atoms. Groups are preferred.

In the present invention, two or more kinds of the specific foam stabilizers (F) may be used in combination, and a foam stabilizer other than the specific foam stabilizer may be used in combination. The amount of the specific foam stabilizer (F) used is preferably 0.1 to 5 parts by mass, more preferably 1 to 4 parts by mass, and particularly preferably 2 to 3 parts by mass, relative to 100 parts by mass of the polyol compound. .

(Isocyanate Compound) In the present invention, the isocyanate compound is not particularly limited, but is an aromatic, alicyclic, or aliphatic polyisocyanate having two or more isocyanate groups; Mixtures of two or more kinds; modified polyisocyanates obtained by modifying these, and the like can be mentioned. As specific examples, tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymethylene polyphenyl isocyanate (common name: crude MD
I), polyisocyanates such as xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI) and hexamethylene diisocyanate (HMDI), or prepolymer-type modified products or nurate modified products thereof,
Examples include urea-modified products and carbodiimide-modified products.
Of these, TDI, MDI, crude MDI, or modified products thereof are preferable.

(Catalyst) The catalyst used in the present invention is not particularly limited as long as it is a catalyst that accelerates the urethanization reaction. For example, triethylenediamine, bis (2
-Dimethylaminoethyl) ether, N, N, N ',
Examples thereof include tertiary amines such as N′-tetramethylhexamethylenediamine; carboxylic acid metal salts such as potassium acetate and potassium 2-ethylhexanoate; and organic metal compounds such as dibutyltin dilaurate.

(Other compounding agents) In the present invention, in addition to the above-mentioned polyol compound, isocyanate compound, foaming agent, foam stabilizer and catalyst, any compounding agent can be used. Compounding agents include fillers such as calcium carbonate and barium sulfate;
Antioxidants such as antioxidants and ultraviolet absorbers; flame retardants, plasticizers, colorants, antifungal agents, foam breaking agents, dispersants, discoloration inhibitors and the like.

(Foaming Device) The method for producing a rigid foam of the present invention can be effectively applied to any foaming device that can use a foaming agent that is gaseous at room temperature. It can be used in any of a high-pressure foaming device, a low-pressure foaming device, and a simplified (low-pressure) foaming device, and is particularly suitable for a low-pressure foaming device and a simplified foaming device. The simple foaming device is preferably a simple foaming device that operates only by operating the pressure of the gas supplied from the gas cylinder.

FIG. 1 shows a schematic structure of an example of this simple foaming apparatus. The simple foaming apparatus shown in FIG. 1 is a cylinder 1 on the active hydrogen compound side filled with an active hydrogen compound or the like, a cylinder 2 on the isocyanate compound side filled with an isocyanate compound or the like, or for discharging these raw materials from the cylinder. An inert gas cylinder 3 filled with an inert pressurized gas such as nitrogen gas, a solvent cylinder 4 filled with a cleaning solvent,
It has a flow controller 5 for controlling the discharge amount of the raw materials, and a static mixer 6 for uniformly mixing the raw materials discharged from the two tanks.

This foaming device operates only by operating the pressure of the gas such as nitrogen supplied from the inert gas cylinder 3, and from the two cylinders 1 and 2 in which the active hydrogen compound and the isocyanate compound are separately filled. It is for discharging and mixing. An example of such a simple foaming device is Auto Floss (produced by Asahi Glass Co., Ltd.). This is (1) easier to reduce the injection amount because it has better fluidity than conventional low-pressure foaming machines and high-pressure foaming machines, and (2) large because the foaming pressure is low. It does not require mold clamping equipment. (3) As a result, it has the features of reducing equipment investment.

The rigid foam manufacturing method of the present invention is suitable for manufacturing a heat insulating panel used for a vending machine, a refrigerator, a freezer, a freezer warehouse, a cold storage warehouse, a cold storage warehouse, a cold storage vehicle, and a building material. It is also suitable for producing rigid foams.

[0042]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

Polyols A1 to A4 and B shown below
1 to B5 were used in formulations C1 to C7 shown in Table 1. However, the numerical values in Table 1 represent parts by mass. Table 2 shows the foam stabilizers used. Polyol A1: A polyoxyalkylene polyol having a hydroxyl value of 67 mgKOH / g and a proportion of oxyethylene groups of 7% by mass, obtained by reacting propylene oxide and ethylene oxide with glycerin as an initiator. Polyol A2: A polyoxyalkylene polyol having a hydroxyl value of 67 mgKOH / g and an oxyethylene group ratio of 13% by mass, obtained by reacting propylene oxide and ethylene oxide with glycerin as an initiator. Polyol A3: Polyoxyalkylene polyol having a hydroxyl value of 67 mgKOH / g and a proportion of oxyethylene groups of 20% by mass, obtained by reacting propylene oxide and ethylene oxide with glycerin as an initiator. Polyol A4: A polyoxyalkylene polyol having a hydroxyl value of 42 mgKOH / g and a proportion of oxyethylene groups of 20% by mass, obtained by reacting propylene oxide and ethylene oxide with glycerin as an initiator. Polyol B1: Hydroxyl value of 170 mg obtained by reacting propylene oxide with glycerin as an initiator
A polyoxyalkylene polyol that is KOH / g. Polyol B2: Hydroxyl value of 67 mgK obtained by reacting propylene oxide with glycerin as an initiator
A polyoxyalkylene polyol that is OH / g. Polyol B3: A polyoxyalkylene polyol having a hydroxyl value of 450 mgKOH / g, obtained by reacting propylene oxide with a sucrose / glycerin mixing initiator. Polyol B4: hydroxyl value of 420 mg obtained by reacting propylene oxide with glycerin as an initiator
A polyoxyalkylene polyol that is KOH / g. Polyol B5: Hydroxyl value of 350 mgKOH / g obtained by reacting propylene oxide and ethylene oxide with a sucrose / ethanolamine mixed initiator.
And a polyoxyalkylene polyol in which the proportion of oxyethylene groups is 10% by mass.

[0044]

[Table 1]

[0045]

[Table 2]

The following foam raw materials were used for evaluation. 100 parts by mass of a polyol mixture having a composition selected from C1 to C7, 2 parts by mass of water, 3.5 parts by mass of the silicone type foam stabilizer shown in Table 2, and N, N-dimethylcyclohexylamine as a catalyst were added to the vat. The necessary amount was added so that the gel time was 135 seconds, and these were well mixed with a stirrer and stirred to obtain a polyol system liquid. This polyol system liquid was transferred, weighed and filled into a predetermined cylinder of a foaming apparatus. The foaming agent shown below had a core density of 28 ± 2 when it was freely foamed (for example, when it was foamed in an open box).
It was added so as to be kg / m ³ . That is, although the amount varies depending on the foaming agent, about 30 to about 40 parts by mass of the foaming agent was added to 100 parts by mass of the polyol mixture. However, a high-pressure injection facility was used to add HFC-134a. Crude MDI (MR-200, manufactured by Nippon Polyurethane Industry Co., Ltd.) was used as the isocyanate compound, and the cylinder was similarly weighed and filled. Foaming agent H1: HFC-245fa / 134a = 40/6
0 (mass ratio) mixed foaming agent H2: HFC-245fa Foaming agent H3: HFC-134a.

The foams and the like were evaluated by the following methods.
The polyol system liquid and the isocyanate compound were adjusted so that the mixing ratio was 110 in terms of isocyanate index, and foamed. 600mm using a predetermined foaming device
The raw material was poured into an aluminum mold of × 900 mm × 50 mm and foamed at room temperature. Regarding the degree of generation of voids, the appearance of the sample (foamed body) obtained by taking out from the mold was visually determined. For dimensional stability and thermal conductivity, cut out a sample piece of a predetermined size from the sample,
The measurement described below was performed. Regarding the evaluation of the compatibility (mixability), a foaming agent and a polyol system liquid were filled in a pressure-resistant transparent glass container, and the appearance was visually judged. A high-pressure injection facility was used to fill the foaming agent.

Tables 3 and 4 show the results of the combination of the polyol mixture and the foam stabilizer and the foams produced.
Examples 1 to 24 are shown. Note that Examples 1 to 12 are examples in which a high-pressure foaming device is used as a foaming device, and Examples 13 to 24 are examples in which a simple foaming device is used as a foaming device. Examples 1-
9 and Examples 13 to 21 are Examples, and Examples 10 to 12 and Examples 22 to 24 are Comparative Examples. The criteria for compatibility evaluation were as follows: ○: transparent and no separation, no problem in use, Δ: cloudy but no separation, no problem in use. The criteria for evaluating the degree of occurrence of voids were as follows: ⊚: Almost no voids can be used, ◯: There are a few voids but no problems in use, ×: Many voids are problems in use. The dimensional stability was measured by storing the sample piece in an atmosphere of 70 ° C. and 95% relative humidity for 24 hours.
%). However, the size of the sample piece is 30 mm x 3
It was set to 0 mm × 30 mm. Thermal conductivity (unit: mW / m ・
K) is the Auto Lambda HC-047 type (made by Eiko Seiki Co., Ltd.)
Was measured using. However, the size of the sample piece is 200m
It was set to m × 200 mm × 25 mm.

(High Pressure Foaming Device) 28 kg of the polyol system liquid was transferred, weighed and filled into a 50 kg cylinder for the polyol component. High-pressure foaming equipment PU-50 (PE
C) was used to mold a rigid foam under the conditions of a liquid temperature of 25 ° C. (for both liquids), a reaction mixture discharge rate of 20 kg / min, and a discharge pressure of 120 kg / cm ² (for both liquids).

(Simplified foaming device) 7 kg of the polyol system liquid was transferred to a 10 kg cylinder for the polyol component, weighed and filled. After the filling is completed, the two liquid cylinders are placed in a heating chamber controlled at 28 ° C. ± 2 ° C., and the liquid temperature is adjusted to 28 to 30 ° C., and a simple foaming device (Asahi Glass Co., Ltd.) is used. Was used to make a rigid foam.

[0051]

[Table 3]

[0052]

[Table 4]

As is clear from the results of the above test, the one using the specific polyol (A) of the present invention at the time of producing a rigid foam has excellent compatibility, and the appearance of the obtained foam,
It was found that the dimensional stability and thermal conductivity were also excellent. In particular, the one using the specific foam stabilizer (F) had a very good appearance. On the other hand, when the specific polyol (A) was not used, many voids were generated and the appearance was poor.

[0054]

INDUSTRIAL APPLICABILITY The present invention has an effect that a foamed synthetic resin having a good surface appearance of a panel can be produced without using a chlorine-containing foaming agent which may damage the ozone layer.

[Brief description of drawings]

FIG. 1 is a schematic view of a configuration of an example of a simple foaming device used in the present invention.

[Explanation of symbols]

1: active hydrogen compound side cylinder 2: Isocyanate compound side cylinder 3: Inert gas cylinder 4: Solvent cylinder 5: Flow controller 6: Static mixer

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiromichi Hotta             25 Asahi, Towada, Kazasu-machi, Kashima-gun, Ibaraki             Glass Urethane Co., Ltd. F-term (reference) 4J034 BA03 DA01 DB03 DB07 DC02                       DC43 DC50 DG03 DG04 DG05                       DG06 DG08 DG10 HA01 HA07                       HA11 HB11 HC03 HC12 HC13                       HC61 HC64 HC67 HC71 KA04                       KB05 KE02 NA02 NA08 NA09                       PA05 QC02

Claims (5)

[Claims] 1. A method for producing a rigid polyurethane foam by reacting a polyol compound and an isocyanate compound in the presence of a foaming agent, a foam stabilizer and a catalyst, wherein at least a part of the foaming agent has a boiling point of 20 ° C. or less. The following polyol (A) was used as a polyol compound.
A method for producing a rigid polyurethane foam, which comprises using a polyol mixture containing 5 to 30% by mass. However, the polyol (A) has a hydroxyl value of 200 mgKO
It is less than H / g and is a polyoxyalkylene polyol containing oxyethylene groups in an amount of 5 to 40% by mass based on the entire polyol (A). 2. The organic compound having a boiling point of 20 ° C. or lower used as the foaming agent contains 1,1,1,3,3-pentafluoropropane and / or 1,1,1,2-tetrafluoroethane. The method for producing a rigid polyurethane foam according to claim 1. 3. A fluorinated compound comprising 1,1,1,3,3-pentafluoropropane and 1,1,1,2-tetrafluoroethane as an organic compound having a boiling point of 20 ° C. or lower used as the foaming agent. The method for producing a rigid polyurethane foam according to claim 2, comprising a hydrocarbon mixture, wherein the proportion of 1,1,1,3,3-pentafluoropropane in the fluorinated hydrocarbon mixture is 1 to 99% by mass. . 4. The rigid polyurethane foam according to claim 1, 2 or 3, wherein the following foam stabilizer (F) is used as the foam stabilizer in an amount of 0.1 to 5 parts by mass based on 100 parts by mass of the entire polyol compound. Manufacturing method. However, the foam stabilizer (F) is a silicone-based foam stabilizer obtained by grafting a polyoxyalkylene chain on a polysiloxane chain, and the polysiloxane chain has a chain length of 2000 to 3000. Has a chain length of 1000 to 2000, a graft number of 1.5 to 2.5, does not have a hydroxyl group at the polyoxyalkylene chain terminal, and the ratio of the polysiloxane chain to the entire foam stabilizer is 30 to. The silicone foam stabilizer is 50% by mass. 5. The method for producing a rigid polyurethane foam according to claim 1, wherein a simple foaming device that operates only by operating a pressure of a gas supplied from a gas cylinder is used as the foaming device.