JP3269590B2 - Method for producing polyurethane foam - Google Patents

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 a novel polyurethane foam. More specifically, the present invention relates to a method for producing a rigid polyurethane foam having excellent filling properties, heat insulation properties and low-temperature dimensional stability without substantially using a catalyst component usually used for accelerating a polyurethane conversion reaction.

[0002]

2. Description of the Related Art Polyurethane foams are easy to control in molding density, product hardness, and various physical properties, and have good moldability, so that rigid foams, semi-rigid foams, and flexible foams are used. As used in many industrial fields. As a method for producing these polyurethanes, a polyisocyanate component and a polyol component are used as a catalyst for producing polyurethane, and a tertiary amine or an organic metal is used to accelerate a curing reaction or a foaming reaction, so that industrial production is possible. Is a common method.

[0003] Of these catalysts for producing polyurethanes, tertiary amines are particularly useful and widely used for controlling the balance of the reaction, but often have a strong irritating odor or skin irritation. It had the drawback of reducing the commercial value due to environmental problems and its odor. Furthermore, when molding rigid polyurethane foam etc. by mold foaming such as refrigerators and panels,
Improvement of the filling property due to the resin fluidity in the mold is required, and therefore, a formulation that can reduce the density with good yield has been desired.

In recent years, in order to protect the ozone layer in the atmosphere, use of chlorofluorocarbons used as a foaming agent has been regulated, and trichlorofluoromethane (R-11) which has been conventionally used for producing rigid polyurethane foams has been regulated.
Are also included in the regulation, so how to reduce trichlorofluoromethane is a problem. Examples of the reduction method include a method of reducing the amount of trichlorofluoromethane used and increasing the amount of water (so-called chlorofluorocarbon reduction prescription), chlorodifluoromethane (R-22) having a smaller ozone depletion potential (ODP) than trichlorofluoromethane, and , 1,1
-Trichlorodifluoroethane (R-142b), 1,
1-dichloro 2,2,2-trifluoroethane (R-1
23), 1,1,1-dichlorofluoroethane (R-1
It has been proposed to use 41b). In addition, technology to use low-boiling hydrocarbons as blowing agents that do not destroy the ozone layer at all is being developed (REWiedermann e
t al., Proceeding of the SPI / ISOPA Polyurethanes W
orld Congress 1991, Technomic Publishing Co., In
c., Lancaster / USA, 1991, 408-411).

However, these compounds have the disadvantage that the polyol compatibility is low and the thermal conductivity is about 20% higher than that of the conventional R-11. Thermal conductivity is the most important issue for rigid foams used primarily as insulation. For example, when used as a heat insulating material for an electric refrigerator or the like, problems such as an increase in power consumption and a decrease in the volume ratio in the refrigerator can be considered. Further, since the usable amount of the foaming agent is reduced due to the low compatibility, it is necessary to relatively increase the amount of water to be added. For this reason, the thermal conductivity is further increased, which causes problems such as filling properties. In order to solve the above problems, it is necessary to develop a method for producing a polyurethane foam in which the thermal conductivity when using hydrocarbons as a foaming agent in producing a polyurethane foam is smaller than in the past. In other words, there has been a demand for a method of developing a method for producing a polyurethane foam that improves heat insulation.

In view of the above demands in the art, as a means for improving the heat insulating property in the conventional production of polyurethane, there are (1) a method in which a terminal hydroxyl group of a polyol is made primary and the reactivity to isocyanate is increased. 2)
A polymerization reaction promoting catalyst is used. (3) The initial stage of the reaction is accelerated by increasing the amount of the catalyst. (4) The free density is set relatively high (0.025 to 0.030 kg / m ³ ), and the overpack ratio is reduced. And (5) reducing the amount of water added, or (6) increasing the average number of functional groups or the average hydroxyl value of the polyol component. However, these methods cannot simultaneously satisfy the heat insulating property, the filling property, the adhesive property and the like.

For example, (1), (2) and (3),
In the method (6), the heat insulating property and the adhesive property are improved because the gelling of the resin is preferentially promoted, but the filling property is extremely deteriorated. In addition, it is pointed out that the methods (4) and (5) suppress the foaming reaction, and have the adverse effect of improving the filling property. For these reasons, there has been a need in the art for the development of a method for producing a polyurethane foam that can simultaneously satisfy the heat insulating property, the filling property, the adhesive property, and the like.

[0008]

Means for Solving the Problems As a result of intensive studies to solve these problems, the present inventors have found that when a polyisocyanate component and a polyol component are reacted in the presence of a blowing agent, a polyurethane foam is produced. By using a tertiary amino alcohol having a specific structure as at least a part of the polyol component, and using low-boiling hydrocarbons as a blowing agent in place of chlorofluorocarbon, the tertiary amino alcohol is substantially eliminated.
Without using a catalyst component such as secondary amine, it is possible to produce a polyurethane foam,
Further, they have found that the polyurethane foam obtained by the method has improved properties such as filling properties, heat insulation properties and adhesive properties as compared with conventional products, and have completed the present invention.

That is, the gist of the present invention is to produce a polyurethane foam by reacting a polyisocyanate component and a polyol component in the presence of an auxiliary agent containing a foaming agent. (I)

[0010]

Embedded image

[In the formula, R ₁ is a linear or branched alkylene group having 2 to 24 carbon atoms, a cycloalkylene group, an aralkylene group, or-(CH ₂ CH ₂ O) _x- (CH ₂ CH
₂ ) _y- (where x is 0 or a positive number and y is a positive number), R ₂ is a linear or branched alkyl or aralkyl group having 1 to 9 carbon atoms, ₃ represents R ₁ OH or R ₂ , and the average degree of polymerization n represents a positive number of 2 to 50. A polyurethane foam, characterized by using one or more tertiary amino alcohols represented by formula (I) and one or more selected from the group consisting of 2-methylbutane, n-pentane and cyclopentane as a blowing agent. It relates to a manufacturing method.

As the polyol component used in the present invention, at least a part of the third component represented by the general formula (I)
It is characterized by using a graded amino alcohol. Since the tertiary amino alcohol represented by the general formula (I) has a tertiary amino group in its molecular skeleton, the tertiary amino alcohol has catalytic performance for the reaction between the polyisocyanate component and the active hydrogen-containing compound, and further has a terminal property. As such, it has hydroxyl groups and also reacts with isocyanate groups. Further, since it is a diol type, it is a compound which does not inhibit the increase in the molecular weight of the polyurethane resin. Therefore, the resinification reaction is promoted as compared with the conventional reaction using an amine catalyst, whereby the cells can be miniaturized in the initial stage of the reaction, and the heat insulating property is improved, and the efficiency of taking the foamed gas into the cells is improved. In order to increase, the filling property also improves. In addition, the usual third
It has a terminal hydroxyl group as compared with a secondary amine catalyst and has a higher boiling point, which reduces the odor of itself, and because it is incorporated into the polyurethane resin skeleton, there is no odor from the polyurethane resin or polyurethane foam. Is not reduced.

The tertiary amino alcohol represented by the general formula (I) can be easily produced by a known method, and is synthesized, for example, by the method described in JP-A-3-83955. Examples of the tertiary amino alcohol used in the production method of the present invention have a structure represented by the general formula (I), wherein R ₁ is a straight or branched chain having 2 to 24 carbon atoms. Alkylene group, cycloalkylene group, aralkylene group, or — (CH ₂ CH ₂ O) _X —
_{(CH 2 CH 2) y -} ( where, x is 0 or a positive number, preferably 0 to 15 integer, more preferably 0 to 1
It is an integer of 0. y is a positive number, preferably 1 to 15
Is a positive number. ), And is preferably a linear or branched alkylene group having 3 to 9 carbon atoms. Here, the cycloalkylene group may have a substituent, and a cycloalkylene group having, for example, a total of 4 to 24 carbon atoms is used. The aralkylene group has, for example, an alkylene group having 1 to 6 carbon atoms and a total of 7 to 24 carbon atoms. Specifically, it is a divalent group obtained by removing one hydrogen atom from the aromatic ring of an aralkyl group which is an alkyl group having an aromatic ring such as a benzyl group and a phenethyl group. Where n R ₁
May be the same or different.

Here, R ₂ is a linear or branched alkyl group or aralkyl group having 1 to 9 carbon atoms, preferably a linear or branched alkyl group having 1 to 4 carbon atoms.
Wherein the n R ₂ may be the same or different. R ₃ is R ₁ OH or R ₂ , preferably R ₁ O
The H / R ₂ molar ratio is 100/0 to 85/15. The average degree of polymerization n is a positive number of 2 to 50, preferably a positive number of 2 to 10.

A third compound having a structure represented by the general formula (I)
In grade amino alcohol, or the carbon number of R ₁ is greater than 9, or average when polymerization degree n is greater than 10, the molecular weight of a tertiary amino alcohol obtained is increased, also the R ₂ carbon atoms, the structure Tends to have a high viscosity and become difficult to use. On the other hand, when the carbon number of R ₁ is smaller than 2 and the average degree of polymerization n is smaller than 2, the content of the tertiary amino group in the molecular skeleton becomes too small, and the expected catalytic performance cannot be obtained. As described above, within the range satisfying the performance as a polyol, the third skeleton in the molecular skeleton thereof may be used.
By selecting the content and molecular weight of the tertiary amino group, the molecular weight of the side chain, and the structure, tertiary amino alcohols having various catalytic performances suitable for the required reactivity can be obtained, and other tertiary amino alcohols can be obtained. Various polyurethanes can be produced without the use of components.

In the method for producing a polyurethane foam of the present invention, the tertiary amino alcohol represented by the general formula (I) can be used in any proportion as one of the polyol components, and can control the catalyst performance, The required shape and physical properties can be obtained by combining with the polyol of the above. In particular, the amount of the tertiary amino alcohol represented by the general formula (I) in the method for producing a polyurethane foam of the present invention is preferably 1 to 50% by weight, more preferably 1 to 30% by weight in the polyol component. The tertiary amino alcohols represented by the general formula (I) used in the present invention can be used alone or in combination of two or more.

In the method for producing a polyurethane foam of the present invention, other polyols used as a polyol component include generally known polyester polyols,
Polyether polyols and the like can be used. For example, polyester polyols produced from ordinary dibasic acids and polyhydric alcohols, polyhydric alcohols such as sucrose, and polyhydric amines such as triethylenediamine, 1,3-propanediamine, isophoronediamine and ethylene oxide and / or propylene Examples thereof include polyether polyols obtained by adding an oxide. These polyols can be used alone or as a mixture of two or more.

The polyisocyanate component used in the production method of the present invention is not particularly limited as long as it is a compound having two or more isocyanate groups.
Any of aromatic, aliphatic or alicyclic polyisocyanate compounds, a mixture of two or more thereof, and a modified polyisocyanate obtained by modifying them may be used. For example, tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate,
There are polyisocyanates such as isophorone diisocyanate, hexamethylene diisocyanate, polymethylene polyphenyl polyisocyanate (crude MDI) and modified polyisocyanates thereof, for example, carbodiimide modified, buret modified, dimer, trimer and the like. And a prepolymer of a terminal isocyanate group of a polyisocyanate and an active hydrogen-containing compound.

In the method for producing a polyurethane foam of the present invention, at least one selected from the group consisting of 2-methylbutane, n-pentane and cyclopentane is used as a blowing agent. The amount of these foaming agents is not particularly limited, but is usually 5 to 30 parts by weight, preferably 10 to 20 parts by weight, per 100 parts by weight of the total amount of the polyol component. Of course, it is also possible to use an amount outside this range depending on the type of polyurethane foam. According to the production method of the present invention, a polyurethane foam having excellent physical properties can be obtained even when such an alternative foaming agent having an ozone destruction coefficient of 0 is used, which is effective in protecting the ozone layer in the atmosphere. .

In the method for producing a polyurethane foam of the present invention, in addition to the above-mentioned polyisocyanate component, polyol component and foaming agent, if necessary, a surfactant,
It is produced by a conventional method using a foam stabilizer, a coloring agent, a flame retardant, a stabilizer and the like. The types and amounts of these additives can be sufficiently used within the types and usage ranges usually used.

In the method for producing a polyurethane foam of the present invention, the use of a tertiary amino alcohol as at least a part of the polyol component substantially eliminates the need for a catalyst component.
The use of a usual catalyst is also possible because it is necessary to further improve the processability. Such a catalyst is not particularly limited, but a conventionally known amine catalyst or metal catalyst can be used. Commonly known amine catalysts include, for example, N, N, N ', N'-tetramethylhexamethylenediamine, N, N, N', N'-tetramethylpropylenediamine, N, N, N ', N' , N ",-pentamethyldiethylenetriamine, N, N, N ', N'-tetramethylethylenediamine, N-methyl-N'-dimethylaminoethylpiperazine, N, N-dimethylaminocyclohexylamine, bis (dimethylaminoethyl ) Ether, tris (N, N-dimethylaminopropyl) hexahydro-s-triazine, methylmorpholine, ethylmorpholine, triethylenediamine, 1-methylimidazole, 1,2-dimethylimidazole, 1-isobutyl-2-methylimidazole and the like. is there. Examples of the metal catalyst include tin octoate, tin dibutyl dilaurate, and lead octoate. These catalysts can be used alone or as a mixture of two or more kinds in combination with the tertiary amino alcohol represented by the general formula (I).

Further, a crosslinking agent can be used if necessary. Such crosslinking agents include ethylene glycol, propylene glycol, diethylene glycol, 1,4-
Glycols such as butanediol, glycerin,
Polyhydric alcohols such as pentaerythritol and sorbitan, alkanolamines such as diethanolamine and triethanolamine, aliphatic polyamines such as ethylenediamine and diethylenetriamine, and aromatic diamines such as 4,4-diphenylmethanediamine can be used.

As the polyisocyanate component and the polyol component used in the method for producing a polyurethane foam of the present invention, any of those exemplified above can be used, and other optional components may be used as long as they are commonly used for producing polyurethane. Either can be used. The present invention provides a method for producing a polyurethane foam, particularly a rigid polyurethane foam. As an example, a method for producing a polyurethane foam in which the polyurethane is a rigid polyurethane will be described below.

In producing a rigid polyurethane foam, the polyol component used has an average hydroxyl value of 30.
Desirably, it is 0 or more. In the production of rigid polyurethane foam, it is important to balance the gas generation rate by the reaction and the curing rate of the resin in order to improve the filling property, and when the gas generation rate is faster than the curing rate of the resin, The gas is not sufficiently taken in, the required foam volume cannot be obtained, and the filling property is poor. When the curing speed of the resin is higher than the gas generation speed, the resin viscosity increases, so-called liquid flow decreases, and the filling property of the rigid polyurethane foam decreases.

In the production of a rigid polyurethane foam, even when water and trichlorofluoromethane are used in a usual ratio as a blowing agent, the ratio of polyol, catalyst or the like is changed for reasons such as improvement in productivity. When the curing speed of the resin is increased, the balance between the gas generation speed required for the filling property and the curing speed of the resin is lost, and the filling property of the rigid polyurethane foam is reduced. However, when the tertiary amino alcohol represented by the general formula (I) according to the present invention is used as all or a part of the polyol component, resinification at the initial stage of the reaction is promoted and gasification of trichlorofluoromethane is promoted at the same time. Therefore, the balance between the gas generation speed required for filling and the curing speed of the resin is maintained, and the filling is further improved.

In the present invention, at least one selected from the group consisting of 2-methylbutane, n-pentane, and cyclopentane is used as a blowing agent, but a tertiary tertiary compound represented by the general formula (I) according to the present invention is used. By using an amino alcohol, the resinification reaction rate is accelerated, and a decrease in the filling property of the rigid polyurethane foam can be prevented.

As the polyisocyanate component and the polyol component used in the method for producing a rigid polyurethane foam of the present invention, any of the above-mentioned ones can be used, and other optional components are those usually used for producing a rigid polyurethane foam. Any can be used. The reaction conditions during production are not particularly limited. In the production of the polyurethane foam of the present invention, the mixture A containing the above-mentioned polyol component as a main component and the mixture B containing the above-mentioned polyisocyanate component as a main component are mixed and reacted. It is preferable to mix in the mixture A, and other components except the polyol component and the polyisocyanate component are usually mixed in the mixture A or B. The rigid polyurethane foam produced in this manner has improved properties such as filling properties, heat insulation properties, and adhesive properties.

[0028]

The present invention will be described in detail with reference to the following examples, but the present invention is not limited to these examples. Examples 1 to 28 and Comparative Examples 1 to 5 The tertiary amino alcohol represented by the general formula (I) used in this example was prepared by a known method (ie, JP-A-3-8395).
No. 5, published by No. 5), four types of amino alcohols A, B, C and D shown in Table 1 were synthesized.

[0029]

[Table 1]

Table 2 shows the formulations of Examples and Comparative Examples.
-4 are shown. Numerical values indicate parts by weight unless otherwise specified. At this time, the polyol was 70 parts of an aromatic amine polyol (OHV = 450) manufactured by Asahi Ohrin Co., Ltd., 20 parts of a sugar-based polyether polyol (OHV = 530) manufactured by Sumitomo Bayer Urethane Co., Ltd., and Mitsui Toatsu Chemicals, Inc. Glycerin-based polyether polyol (OHV = 23)
5) A mixture of 10 parts was used. 1.5 parts of L-5340 manufactured by Nippon Unicar Co., Ltd. was used as a foam stabilizer, and tetramethylhexamethylenediamine (KLNo. 1) manufactured by Kao Corporation was used as a catalyst. As a polyisocyanate component, TR-50BX manufactured by Mitsui Toatsu Chemicals, Inc. was used at NCO / OH = 1.05.

The evaluation was performed by the following method. (1) Free density: inner dimensions 150 x 150 x 200 mm
Material Density when foaming is performed in a veneer mold (kg
/ M ³ ) (2) Fillability: Length of molded product (cm / 350 g) when 350 g of raw material is injected into an aluminum inverted L-shaped mold controlled at 40 ° C. shown in FIG. Thermal conductivity: Anacon model 88 (measurement sample 200 × 200 × 25 mm) Measurement temperature 23.85 ° C.

[0032]

[Table 2]

[0033]

[Table 3]

[0034]

[Table 4]

As apparent from Tables 2 to 4, Comparative Example 1
-5, CFC-11 as hydrocarbon blowing agent, n
In the case of using -pentane, 2-methylbutane or cyclopentane, a product satisfying both the thermal conductivity and the filling property was not obtained. However, when the tertiary amino alcohol is used as a part of the polyol in the present invention, the thermal conductivity becomes about 1
5%, and at the same time it is possible to improve the fillability by about 5 to 10%.

[0036]

According to the present invention, the use of low-boiling hydrocarbons which do not destroy the ozone layer at all as the blowing agent and the tertiary amino alcohols of the present invention as at least a part of the polyol have been difficult to achieve. This has made it possible to simultaneously improve the filling property and the thermal conductivity.

[Brief description of the drawings]

FIG. 1 is a view showing an inverted L-shaped mold frame made of aluminum used in Examples.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takayuki Nomura 1130 Nishihama, Wakayama City, Wakayama Prefecture (56) References JP-A-5-97954 (JP, A) JP-A-5-97955 (JP, A) 3-152160 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08G 18/00-18/87

Claims (5)

(57) [Claims] When producing a polyurethane foam by reacting a polyisocyanate component and a polyol component in the presence of an auxiliary agent containing a foaming agent, at least a part of the polyol component has the following general formula (I): ] [Wherein, R ₁ represents a linear or branched alkylene group having 2 to 24 carbon atoms, a cycloalkylene group, an aralkylene group, or-(CH ₂ CH ₂ O) _x- (CH ₂ CH ₂ ) _y- ( , X is 0 or a positive number, and y is a positive number), R ₂ represents a linear or branched alkyl group or aralkyl group having 1 to 9 carbon atoms, and R ₃ represents R ₁ OH or It represents R _2, average polymerization degree n represents a positive number of 2 to 50. A polyurethane foam, characterized by using one or more tertiary amino alcohols represented by formula (I) and one or more selected from the group consisting of 2-methylbutane, n-pentane and cyclopentane as a blowing agent. Production method. 2. The method according to claim 1, wherein 1 to 50% by weight of the polyol component is a tertiary amino alcohol represented by the general formula (I). 3. The method according to claim 1, wherein the blowing agent is cyclopentane.
The manufacturing method as described. 4. The method according to claim 1, wherein the polyurethane foam is a rigid polyurethane foam. 5. The polyol component having an average hydroxyl value of 300.
The manufacturing method according to claim 1, which is the above.