JP5269445B2 - Method for producing rigid polyisocyanurate foam - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process for producing hard polyisocyanurate foam having sufficient strength and fire retardancy in spite of low density, and excellent in impact absorption. <P>SOLUTION: A process for production of hard polyisocyanurate foam includes reacting a polyol component (A) with a polyisocyanate component (B). The polyol component (A) includes a polyether polyol (A1) having an average hydroxyl number of 6 to 8 and an average hydroxyl value of 300 to 700 mgKOH/g, a polyether mono-ol (A2) containing an aromatic ring and having an average hydroxyl value of 40 to 120 mgKOH/g, and water (A3) as a blowing agent. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a method for producing a rigid polyisocyanurate foam.

  Rigid polyisocyanurate foam is a foam having an isocyanurate ring obtained by a trimerization reaction of an isocyanate group, and has high flame retardancy compared to rigid polyurethane foam, so that high flame retardancy is required. Widely used in applications.

  In recent years, from the viewpoint of preventing global warming, a method using carbon dioxide generated by the reaction of an isocyanate group and water as a blowing agent has been used as a blowing agent instead of using a low-boiling compound such as hydrofluorocarbons as a blowing agent. It has been. However, in a rigid polyisocyanurate foam using water as a blowing agent, an isocyanate group is required to generate carbon dioxide, unlike the case of using a conventional low boiling point compound as a blowing agent. Therefore, in particular, when producing a low density hard polyisocyanurate foam, a large amount of isocyanate compound is required, so that there is a problem that the physical properties of the hard polyisocyanurate foam other than the flame retardant deteriorate. .

For example, a shock absorber using a rigid polyurethane foam has been reported. However, it is difficult to say that these rigid polyurethane foams have high flame retardancy, and an excess of isocyanate compound is included in order for these rigid polyurethane foams to contain isocyanurate rings. When used in the above, there is a problem that physical properties other than flame retardancy such as shock absorption deteriorate.
JP-A-8-193118

  The present invention has been made in view of the above problems, and the object thereof is a rigid polyisocyanurate having sufficient strength and flame retardancy even at low density and excellent in impact absorption. It is to provide a method for manufacturing a foam.

  As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention have found that the above-mentioned problems can be solved by using a specific component as the rigid polyisocyanurate foam, and the present invention has been completed. It was.

That is, the method for producing a rigid polyisocyanurate foam according to the present invention is a method for producing a rigid polyisocyanurate foam obtained by reacting a polyol component (A) with a polyisocyanate component (B). A) is a polyether polyol (A1) having an average number of hydroxyl groups of 6 to 8 and an average hydroxyl value of 300 to 700 mgKOH / g (hereinafter sometimes referred to as “polyol (A1)”), an aromatic ring. Polyether monool (A2) having an average hydroxyl value of 40 to 120 mg KOH / g (hereinafter sometimes referred to as “monool (A2)”), and water (A3) as a blowing agent are those containing, blending ratio of the polyether mono-ol of the (A1) said polyether polyol (A2) is, in weight ratio A 35 / 65-65 / 35, and the isocyanate index is characterized in that it is a 150 to 250.

In the method for producing a rigid polyisocyanurate foam of the present invention, the blending ratio of the polyether polyol and the polyether monool (A2) is preferably 35/65 to 50/50 by weight .

In addition, the polyol component (A) contains a polyether polyol (A1) having an average hydroxyl number of 6 to 8 and an average hydroxyl value of 300 to 700 mgKOH / g, an aromatic ring, and an average hydroxyl value of 40 to 40. In addition to the polyether monool (A2) of 120 mg KOH / g, it is preferable not to contain a polyether polyol .

  Furthermore, the impact-absorbing material of the present invention is obtained by any one of the above-described methods for producing a rigid polyisocyanurate foam.

  According to the method for producing a rigid polyisocyanurate foam of the present invention, it is possible to obtain a rigid polyisocyanurate foam having sufficient strength and flame retardancy even at low density and excellent in impact absorbing ability.

  The polyether polyol (A1) having an average hydroxyl number of 6 to 8 and an average hydroxyl value of 300 to 700 mgKOH / g used in the present invention is, for example, a low molecular polyol having an average hydroxyl number of 6 to 8 (for example, , Sorbitol, sucrose, and mixtures thereof) include polyether polyols obtained by addition polymerization of alkylene oxide (eg, ethylene oxide, propylene oxide, butylene oxide, etc.) by a known method. These can be used alone or in combination of two or more. When the average number of hydroxyl groups is less than 6, the strength of the rigid polyisocyanurate foam tends to be low, and when it is greater than 8, the rigid polyisocyanurate foam tends to be hard and brittle, and the impact absorption tends to decrease. . Further, when the average hydroxyl value is less than 300 mgKOH / g, the strength of the hard polyisocyanurate foam tends to be low, and when it exceeds 700 mgKOH / g, the hard polyisocyanurate foam tends to be hard and brittle, and the impact absorption is reduced. There is a tendency.

  As the polyether monool (A2) containing an aromatic ring and having an average hydroxyl value of 40 to 120 mgKOH / g used in the present invention, a low molecular monool containing an aromatic ring (for example, phenol, alkylphenol, styrenation) Examples of the phenol monool include polyether monools obtained by addition polymerization of alkylene oxides similar to those used in the production of the polyether polyol (A1) by a known method. These can be used alone or in combination of two or more. If the average hydroxyl value is less than 40 mgKOH / g, the strength of the hard polyisocyanurate foam tends to be low, and if it exceeds 120 mgKOH / g, the flame retardancy of the hard polyisocyanurate foam tends to be reduced.

  Moreover, it is preferable that the mixture ratio of a polyol (A1) and monool (A2) is 25 / 75-75 / 25 by weight ratio, and it is more preferable that it is 35 / 65-65 / 35. If the blending ratio of the polyol (A1) is smaller than the above range, the strength of the hard polyisocyanurate foam tends to be low, and if the blending ratio of the polyol (A1) is large, the hard polyisocyanurate foam is hard and easily brittle. There is a tendency for shock absorption to decrease.

  Water (A3) may be mentioned as a blowing agent used in the present invention, and the amount of the foaming agent can be appropriately adjusted depending on the desired density of the hard polyisocyanurate foam. 2 to 8 parts by weight, preferably 3 to 5 parts by weight. If it is smaller than the above range, foaming of the rigid polyisocyanurate foam tends to be insufficient, and if it is larger than the above range, the rigid polyisocyanurate foam tends to collapse (collapse), and the rigid polyisocyanurate foam is hard and brittle. The impact absorbability tends to decrease.

  In addition to the polyol (A1) and monool (A2), other polyols can be used for the polyol component (A) of the present invention to the extent that the effects of the present invention are not impaired. Examples of such other polyols include conventionally known polyols such as polyether polyols, polyester polyols, and amine polyols other than (A1).

  The polyisocyanate component (B) used in the present invention contains a polyisocyanate compound. Such polyisocyanate compounds are not particularly limited, but for example, aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, araliphatic polyisocyanates such as xylylene diisocyanate, hexamethylene diisocyanate And alicyclic polyisocyanates such as aliphatic polyisocyanate, isophorone diisocyanate, and dicyclohexylmethane diisocyanate. In addition to carbodiimide-modified products and isocyanurate-modified products of the above polyisocyanate compounds, isocyanate group-terminated prepolymers obtained by reacting the polyisocyanate compounds with active hydrogen compounds under an excess of isocyanate groups can also be used. These can be used alone or in combination of two or more. Among these, aromatic polyisocyanate is preferable because of its high reactivity with the polyol component (A), and diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, and mixtures thereof are more preferable.

  The mixing ratio of the polyol component (A) and the polyisocyanate component (B) used in the present invention preferably has an isocyanate index of 120 to 300, more preferably 150 to 250. Here, the isocyanate index is a value obtained by multiplying the number of moles of isocyanate groups with respect to 1 mole of active hydrogen groups contained in the raw material by 100, for example, when 1 mole of isocyanate groups is per mole of active hydrogen groups. Has an isocyanate index of 100. If the isocyanate index is smaller than the above range, the flame retardancy of the hard polyisocyanurate foam tends to be reduced. If the isocyanate index is larger than the above range, the hard polyisocyanurate foam tends to be hard and brittle, and the impact absorption tends to decrease. It is in.

  The polyol (A) of the present invention includes the polyol (A1), the polyol (A2), and the water (A3).

  In the method for producing a rigid polyisocyanurate foam of the present invention, a catalyst, a foam stabilizer, a flame retardant, and the like can be used as an auxiliary agent.

  As the catalyst, conventionally known isocyanurate-forming catalysts and urethanization catalysts can be used.

  Examples of the isocyanuration catalyst include amine compounds such as 2,4,6-tris (dimethylaminomethyl) phenol, 1,3,5-tris (N, N-dimethylaminopropyl) hexahydro-S-triazine, and the like. And triazine compounds, quaternary ammonium salts, alkali metal salts of organic carboxylic acids such as potassium acetate and potassium octylate.

Examples of the urethanization catalyst include triethylamine, N-methylmorpholine, N, N, N ′, N′-tetramethylhexamethylenediamine, N, N, N ′, N′-pentamethyldiethylenetriamine, bis- Examples thereof include tertiary amine compounds such as (2-dimethylaminoethyl) ether, triethylenediamine and dimethylethanolamine, imidazole compounds such as 1-methylimidazole, and organic acid salts thereof.
As the foam stabilizer, conventionally known foam stabilizers for producing polyisocyanurate foams can be used, and examples thereof include silicone foams such as dimethylsiloxane and polyether-modified dimethylsiloxane.

  As the flame retardant, a conventionally known flame retardant for producing polyisocyanurate foam can be used. For example, phosphoric acid such as triethyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, tris (chloropropyl) phosphate, etc. An ester compound is mentioned.

  Furthermore, the polyol component (A) and the polyisocyanate component (B) used in the present invention are blended with a plasticizer, a colorant, an anti-aging agent, an antioxidant, a pigment and the like to the extent that the effects of the present invention are not impaired. be able to.

  The production of the rigid polyisocyanurate foam of the present invention is not particularly limited, but examples thereof include the following method.

  First, as a polyol component (A), polyol (A1), monool (A2), water (A3) as a foaming agent, and auxiliary agents such as a catalyst and a foam stabilizer are mixed in a predetermined amount. Subsequently, a predetermined amount of the polyol component (A) and the polyisocyanate component (B) are mixed using a stirrer such as a homodisper, or a low-pressure or high-pressure foaming machine, and the obtained mixed solution is poured into a sealed mold. The hard polyisocyanurate foam is obtained by curing after curing for a predetermined time and then removing the mold.

The density of the rigid polyisocyanurate foam obtained by the production method of the present invention is preferably 40 to 60 kg / m ³ . If it is smaller than the above range, the strength of the rigid polyisocyanurate foam tends to be low, and if it exceeds the above range, the weight of the product using the rigid polyisocyanurate foam increases, and it is used for automobiles and the like. In some cases, it tends to be difficult to realize energy saving.

  The stress at the time of 50% compression strain of the rigid polyisocyanurate foam obtained by the production method of the present invention (hereinafter sometimes referred to as “50% compressive strength”) is 3.0 to 6.0 MPa. Preferably, it is 4.0 to 5.0 MPa. By setting it within the above range, it becomes easy to obtain a rigid polyisocyanurate foam having high strength and excellent shock absorption.

  It is preferable that the effective compression strain of the rigid polyisocyanurate foam obtained by the production method of the present invention has a lower limit of 10 to 40% and an upper limit of 70 to 85%. By setting the upper limit value and the lower limit value of the effective compression strain within the above ranges, excellent impact absorbability can be imparted to the rigid polyisocyanurate foam.

  Here, the effective compressive strain means that the stress is almost constant as indicated by 1-2 in the curve of FIG. 1 showing the relationship between the compressive strain and the stress when the rigid polyisocyanurate foam is statically compressed. It is the range of compression strain that becomes. Note that 1 indicates that the increase in stress in the initial stage of compression is suppressed and the stress becomes substantially constant, and the compressive strain in 1 is the lower limit value of the effective compressive strain. Moreover, 2 shows the place where the stress which has been almost constant starts to increase, and the compressive strain in 2 is the upper limit value of the effective compressive strain.

  The rigid polyisocyanurate foam obtained by the production method of the present invention preferably has a flame retardancy measured according to the UL94 standard of V-0. By setting it within the above range, excellent flame retardancy can be imparted to the rigid polyisocyanurate foam.

  EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited only to an Example. In the examples and comparative examples described later, “parts” and “%” represent parts by weight and weight%, respectively, unless otherwise specified.

  Moreover, the average hydroxyl value of the obtained polyol (A1) and monool (A2) was measured according to JIS K1557.

<Synthesis Example 1>
After adding 182 g of sorbitol and 0.5 g of potassium hydroxide to a glass autoclave, the inside of the autoclave was replaced with nitrogen. Next, 491 g of propylene oxide was introduced while maintaining a temperature of 120 ° C. and a pressure of 0.3 MPa, and an aging reaction was performed for 3 hours. The average hydroxyl value of the obtained polyether polyol (A1-1) was 500 mgKOH / g.

<Synthesis Example 2>
The same operation as in Synthesis Example 1 was performed except that the amount of propylene oxide introduced was 660 g. The average hydroxyl value of the obtained polyether polyol (A1-2) was 400 mgKOH / g.

<Synthesis Example 3>
After adding 182 g of sorbitol and 0.5 g of potassium hydroxide to a glass autoclave, the inside of the autoclave was replaced with nitrogen. Next, 387 g of propylene oxide was introduced while maintaining a temperature of 120 ° C. and a pressure of 0.3 MPa, and an aging reaction was performed for 3 hours. Further, 43 g of ethylene oxide was introduced and ripened for 2 hours. The average hydroxyl value of the obtained polyether polyol (A1-3) was 550 mgKOH / g.

<Synthesis Example 4>
The same operation as in Synthesis Example 1 was performed except that 342 g of sucrose was used instead of sorbitol and the amount of propylene oxide introduced was 656 g. The average hydroxyl value of the obtained polyether polyol (A1-4) was 450 mgKOH / g.

<Synthesis Example 5>
The same operation as in Synthesis Example 1 was performed except that the amount of propylene oxide introduced was changed to 1500 g. The average hydroxyl value of the obtained polyether polyol (A1-5) was 200 mgKOH / g.

<Synthesis Example 6>
After adding 220 g of nonylphenol (manufactured by Yokkaichi Synthesis Co., Ltd.) and 0.3 g of potassium hydroxide to a glass autoclave, the inside of the autoclave was replaced with nitrogen. Next, while maintaining the temperature at 120 ° C. and the pressure at 0.3 MPa, 432 g of ethylene oxide was introduced, and an aging reaction was performed for 2 hours. The average hydroxyl value of the obtained polyether monool (A2-1) was 86 mgKOH / g.

<Synthesis Example 7>
The same operation as in Synthesis Example 6 was performed except that the amount of ethylene oxide introduced was 290 g. The average hydroxyl value of the obtained polyether monool (A2-2) was 110 mgKOH / g.

<Synthesis Example 8>
The same operation as in Synthesis Example 6 was performed except that 100 g of styrenated phenol (trade name: Antage SP, manufactured by Kawaguchi Chemical Industry Co., Ltd.) was used instead of nonylphenol, and the amount of ethylene oxide introduced was 600 g. The average hydroxyl value of the obtained polyether monool (A2-3) was 70 mgKOH / g.

<Synthesis Example 9>
The same operation as in Synthesis Example 6 was performed except that 32 g of methanol was used instead of nonylphenol and the amount of ethylene oxide introduced was 248 g. The average hydroxyl value of the obtained polyether monool (A2-4) was 200 mgKOH / g.

  The polyol component (A) and the isocyanate component (B) were mixed at the blending ratio shown in Table 1 and adjusted to 20 ° C. Subsequently, the polyol component (A) and the isocyanate component (B) were mixed, and then immediately stirred vigorously for 10 seconds at a rotation speed of 4500 rpm using a homodisper (manufactured by Toyo Seiki Co., Ltd.). This was put into a sealed metal mold (15 cm × 15 cm × 5 cm) previously adjusted to 35 ° C., cured at 35 ° C. for 20 minutes, and then demolded to obtain a rigid polyisocyanurate foam.

In this example, the following raw materials were used.
(Catalyst-1)
30% dipropylene glycol solution of bis (2-dimethylaminoethyl) ether (trade name: TOYOCAT ET, manufactured by Tosoh Corporation)
(Catalyst-2)
Tetramethylhexamethylenediamine (trade name: TOYOCAT MR, manufactured by Tosoh Corporation)
(Catalyst-3)
15% dipropylene glycol solution of potassium octylate (trade name: PACCAT 15G, manufactured by Nippon Chemical Industry Co., Ltd.)
(Foam stabilizer)
Polyoxyalkylene / dimethylpolysiloxane copolymer (trade name: Silicon SZ-1671, manufactured by Toray Dow Corning)
(B-1)
Polymethylene polyphenyl polyisocyanate (free isocyanate content: 31% by weight, trade name: Millionate MR-200, manufactured by Nippon Polyurethane Industry Co., Ltd.)

  The physical properties of the rigid polyisocyanurate foam of the present invention were measured by the following methods.

(1) Cure property A case where the hard polyisocyanurate foam was cured by curing in the above method was evaluated as ◯, and a case where the uncured one was cured as x.

(2) Density A 10 cm × 10 cm × 4 cm rectangular parallelepiped was cut out from the obtained hard polyisocyanurate foam so as not to include the foam surface, and the density was determined from its weight.

(3) 50% compressive strength A 5 cm × 5 cm × 3 cm rectangular parallelepiped is cut out from the obtained rigid polyisocyanurate foam so as not to include the foam surface, and is converted into JIS K 7220 by an autograph (5581 type manufactured by Instron). According to the measurement, the stress at 50% compressive strain was read.

(4) Effective compression strain From the obtained rigid polyisocyanurate foam, a 5 cm × 5 cm × 3 cm rectangular parallelepiped was cut out so as not to include the foam surface, and in accordance with JIS K 7220 using an autograph (5581 type manufactured by Instron). Then, the compression strain was measured until it reached 90%, and a curve showing the relationship of “compression strain-stress” as shown in FIG. 1 was obtained. Subsequently, from this curve, the increase in stress at the initial stage of compression is subsided, and the compressive strain at 1 at which the stress becomes substantially constant (the lower limit value of the effective compressive strain), and the stress at which the stress that has been substantially constant begins to increase. The compression strain (the upper limit value of the effective compression strain) was read.

(5) Flame retardancy From the obtained hard polyisocyanurate foam, a 1 cm × 0.5 cm × 10 cm rectangular parallelepiped was cut out so as not to include the foam surface, and measured according to UL94 standard.

  As can be seen from Table 1, the rigid polyisocyanurate foam obtained by the production method of the present invention had good curing properties, 50% compressive strength, effective compressive strain, and flame retardancy.

  On the other hand, as shown in Comparative Example 1, when only the polyol (A1) is used, the upper limit value of the effective compression strain is lowered, so that the impact absorbability is lowered and the flame retardancy is also lowered. Further, as in Comparative Example 2, when only the monool (A2) is used, the curing property is lowered, and further, the lower limit of the effective compressive strain is increased, so that the impact absorbability is lowered. Further, as in Comparative Example 3, when a polyether polyol having an average hydroxyl value lower than that of the polyol (A1) is used, the compressive strength is reduced by 50%. As in Comparative Example 4, the monool (A2) When a polyether monool having a higher average hydroxyl value and no aromatic ring is used, it can be seen that the 50% compressive strength and flame retardancy are reduced.

  Rigid polyisocyanurate foam obtained by the production method of the present invention is used in fields where conventional shock absorbers are used, for example, in applications where high flame retardancy is required among interior materials such as vehicles. Is possible.

It is the figure which showed the relationship between the compressive strain and stress when a rigid polyisocyanurate foam is statically compressed, and is explanatory drawing of the effective compressive strain of a rigid polyisocyanurate foam.

Explanation of symbols

1 The point at which the increase in stress at the initial stage of compression is stopped and the stress becomes almost constant. The compressive strain at this time is the lower limit of the effective compressive strain.
2 This is the point where the stress, which was almost constant, starts to increase, and the compression strain at this time is the upper limit of the effective compression strain.

Claims (4)

A method for producing a rigid polyisocyanurate foam obtained by reacting a polyol component (A) and a polyisocyanate component (B), wherein the polyol component (A) is:
A polyether polyol (A1) having an average hydroxyl number of 6 to 8 and an average hydroxyl value of 300 to 700 mgKOH / g;
A polyether monool (A2) containing an aromatic ring and having an average hydroxyl value of 40 to 120 mg KOH / g;
Water as foaming agent (A3)
And containing
The blending ratio of the polyether polyol of (A1) and the polyether monool of (A2) is 35/65 to 65/35 by weight ratio,
And the manufacturing method of the rigid polyisocyanurate foam characterized by the isocyanate index being 150-250.
2. The rigid poly according to claim 1, wherein a blending ratio of the polyether polyol of (A1) and the polyether monool of (A2) is 35/65 to 50/50 by weight ratio. Method for producing isocyanurate foam.
The polyol component (A) contains a polyether polyol (A1) having an average hydroxyl number of 6-8 and an average hydroxyl value of 300-700 mgKOH / g, an aromatic ring, and an average hydroxyl value of 40-120 mgKOH / The manufacturing method of the rigid polyisocyanurate foam of Claim 1 or 2 which does not contain polyether polyol other than the polyether monool (A2) which is g.
The impact-absorbing material which consists of a rigid polyisocyanurate foam obtained by the manufacturing method of any one of Claims 1-3.

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