JPH1045862A - Method for producing rigid polyurethane foam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a low-density rigid polyurethane foam having good dimensional stability and good adhesion to a surface material even when water is used as a foaming agent, and having excellent water absorption resistance and storage stability. Provide a way. SOLUTION: In the method for producing a rigid polyurethane foam using water as a foaming agent, tolylenediamine-based short-chain polyether polyol, ethylenediamine-based short-chain polyether polyol, glycerin-based long-chain polyether polyol, and dipropylene are used as polyol components. A polyol mixture containing glycol in a specific ratio is used, and a special silicone-based foam stabilizer specified by an average molecular weight, a silicone concentration in a molecule, and an EO / PO ratio is used as a foam stabilizer. In this case, it is preferable that the active hydrogen terminal group in the silicone foam stabilizer is substituted with a substituent which is inactive to isocyanate.

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 rigid polyurethane foam, and more particularly to a method for producing a rigid polyurethane foam, which has excellent dimensional stability and adhesiveness to a face material even when water is used as a foaming agent. The present invention relates to a method for producing a low-density rigid polyurethane foam having water absorption and storage stability.

[0002]

2. Related Background Art In connection with the elimination of CFCs accompanied by destruction of the ozone layer, attention has been paid to a method of using water alone as a foaming agent in the field of rigid polyurethane foam production. Needless to say, this method uses carbon dioxide gas generated by a chemical reaction between water and isocyanate components to foam the carbon dioxide gas.The carbon dioxide gas diffuses to the outside through the closed-cell cell membrane of the rigid polyurethane foam very quickly. Conversely, the velocity of the external gas (nitrogen, oxygen) that diffuses and penetrates through the cell membrane is low, so that the internal pressure in the closed cell tends to be reduced over time and contract.

[0003] Therefore, if the strength of the resin constituting the cell film is low, the foam shrinks abnormally due to the atmospheric pressure, not only lacking in dimensional accuracy but also losing its function as a structure. Therefore, conventionally, in order to increase the strength of the resin, a high-functional, high OH number polyether polyol using shoe close, tolylenediamine, ethylenediamine, etc. as an initiator has been mainly used, and the free foam density is 30 kg / m ³ or more. Had been manufactured.

[0004]

However, as described above, when a high-functionality, high OH-value polyether polyol is frequently used in order to prevent room-temperature shrinkage of a water-foamed rigid polyurethane foam, one of the features of the polyurethane foam is as follows. There was a problem that the self-adhesion performance with the material was reduced. In addition, even if an attempt is made to change the skeletal structure from a closed cell to a partially open cell to facilitate the passage of gas, the density does not decrease (the weight cannot be reduced), and the bubbles become coarse (insulation property becomes poor). Lower), water absorption resistance is deteriorated (rust occurs in a composite with a steel sheet surface material), and a premixed liquid mixture (R liquid) is easily separated and lacks storage stability.

An object of the present invention is that even when water is used alone as a foaming agent, it has low shrinkage at room temperature, excellent dimensional stability, good adhesion to face materials, and sufficient water absorption resistance. Another object of the present invention is to provide a method for producing a low-density rigid polyurethane foam having storage stability.

[0006]

In order to achieve the above-mentioned object, the present invention provides a rigid polyurethane foam in which a polyol component and an isocyanate component are reacted in the presence of water, a tertiary amine catalyst, and a silicone foam stabilizer. And (b) 10-40% by weight of a polyether polyol having an initiator of tolylenediamine (OH value: 460 ± 20), and (b) a polyether polyol having an initiator of ethylenediamine as the polyol component. (OH value 500 ± 20) 20 to 50% by weight and (c) a polyether polyol having glycerin as an initiator (OH value 34 ±
5) A mixture of 15 to 25% by weight and (d) 10 to 25% by weight of (d) dipropylene glycol (OH value 840) is used, and as the silicone foam stabilizer, the average molecular weight is 5,000 to 10,000. Having a silicone concentration of 40 to 50% by weight and an EO / PO ratio (weight ratio of ethylene oxide to propylene oxide contained in the molecule) of 70/30 to 80/20. -The gist is to use a block copolymer.

According to a second aspect of the present invention, in carrying out the method for producing a rigid polyurethane foam according to the first aspect, the average OH value of the polyol mixture is set to 400 to 5.
It is characterized in that it is adjusted to the range of 00.

[0008] Further, the invention according to claim 3 of the present invention is directed to a polystyrene prepared by replacing the active hydrogen terminal group in the molecule of the silicone foam stabilizer with a substituent which is inactive to the isocyanate component. Oxyalkylene glycol
3. The method for producing a polyurethane foam according to claim 1, which is a dimethylpolysiloxane block copolymer, wherein active hydrogen of a polyoxyalkylene glycol chain directly bonded to a silicon atom in the silicone foam stabilizer. The terminal group is characterized in that the terminal group is substituted with a group that does not react with an isocyanate group such as a methoxy group or an acyl group and inactivated for use.

That is, the present invention relates to a method for producing a rigid polyurethane foam using water as a foaming agent, wherein a low-OH-value glycerin is added to a conventional mixed polyol component containing a high-functional, high-OH-value polyether polyol as a main component. It is characterized in that a specific amount of a polyether polyol is added and a specific silicone-based foam stabilizer is used in combination as a foam stabilizer.

The glycerin-based polyether polyol preferably used in carrying out the present invention has an OH value =
A trifunctional long-chain polyol in the range of 34 ± 5, and when the polyol is added in the range of 15 to 25% by weight to the polyol component, the closed cell rate of the rigid polyurethane foam is adjusted to the range of 70 to 80%. Becomes possible. This effectively prevents a decrease in dimensional stability due to gas permeability.

[0011] When the amount of the glycerin-based polyether polyol is less than 15%, the formation of open cells is not sufficient. On the contrary, when the amount of the glycerin-based polyether polyol exceeds 25%, the R premix solution is separated and the storage stability of the composition is increased. In addition to the decrease in the properties, the formation of open cells is excessively advanced, which leads to an increase in water absorption and a decrease in foam strength, which is not preferable.

The types and amounts of the other polyol components used in the present invention are necessary for maintaining the foaming density, strength and heat insulation of the rigid polyurethane foam at the same level as those of conventional foams. That is, the mixed polyol used in the present invention comprises the following components as described above. (A) 10 to 40% by weight of a polyether polyol having an initiator of tolylenediamine (OH value: 460 ± 20);
(B) 20 to 50% by weight of a polyether polyol having an ethylenediamine as an initiator (OH value 500 ± 20);
(C) 15 to 25% by weight of a polyether polyol having glycerin as an initiator (OH number 34 ± 5) and (d) 10 to 25% by weight of dipropylene glycol (OH number 840).

The average OH value of the mixed polyol is as follows:
It is desirable that the adjustment be made in the range of 400 to 500. If the OH value of these mixed polyols is less than 400, the water absorption resistance and storage stability decrease, and if the OH value is more than 500, the viscosity becomes large and molding becomes difficult, and furthermore, the adhesion to the face material is undesirably deteriorated.

The silicone foam stabilizer used in the present invention has an average molecular weight of 5,000 to 10,000, a silicone concentration in the molecule of 40 to 50% by weight, and EO / PO.
A polyoxyalkylene glycol / dimethylpolysiloxane / block copolymer having a ratio in the range of 70/30 to 80/20, particularly preferably a polyoxyalkylene directly bonded to a silicon atom in a silicone foam stabilizer molecule. The active groups are inactivated by replacing the active hydrogen terminal group of the glycol chain with a stable group which does not react with an isocyanate group such as a methoxy group or an acyl group. A specific example is Nihon Unicar Co., Ltd., trade name: S-8
24-36 can be mentioned as a suitable example.

Table 1 shows the properties of silicone foam stabilizers particularly suitable for use in the present invention in comparison with two conventional silicone foam stabilizers. As is clear from this,
This silicone foam stabilizer is characterized in that it is not only different from conventional foam stabilizers in silicone concentration, average molecular weight and EO / PO ratio, but also not reactive with isocyanate. Incidentally, in the conventional silicone foam stabilizers listed in Table 1, even if the polyol component satisfies the requirements, the closed cell rate does not decrease and the dimensional stability is lacking, so that the intended purpose is not achieved.

[0016]

[Table 1]

As the isocyanate component used in the present invention, low viscosity crude MDI is optimal, but general purpose crude MDI may be used. The compounding amount of these isocyanates is used such that the isocyanate index (NCO Index) is in the range of 0.8 to 1.1, similarly to the usual recipe for producing a rigid polyurethane foam.

Suitable catalysts include typical tertiary amine catalysts such as tetramethylhexamethylenediamine (for example, Kaolyzer No. 1 manufactured by Kao Corporation) and bis- (2-dimethylaminoethyl). ) Ether (for example, manufactured by UCC, trade name: NIAX A-1). In using these catalysts, the former is used alone or the former and the latter are used in a quantitative range in which the closed cell ratio can be controlled in the range of 70 to 80%, or the former and the latter are used in an amount of 0/100 to
It is preferred to blend in a 50/50 ratio and use it as a mixed catalyst system. In addition, as a substitute for the caloriser No. 1 in the above-mentioned mixed catalyst system, Sankyo Air Products Co., Ltd., trade name: Dabco-33LV or Kao Corp.
A strong resin-forming catalyst such as NL-30 manufactured by the trade name can also be used.

In addition, the rigid polyurethane foam composition according to the present invention may contain, if necessary, a compound such as trischloroethyl phosphate or tris-β-chloropropyl ether which acts as a viscosity reducing agent and a flame retardant. It goes without saying that an agent can be added as appropriate.

When all of the above requirements are satisfied, control of the closed cell ratio, storage stability of the stock solution, and viscosity (viscosity of 1000 cps / 20 ° C. or less) can be ensured, and dimensional stability and water absorption resistance can be ensured. A rigid polyurethane foam to which practically desired qualities such as adhesiveness are imparted in a well-balanced manner can be obtained.

[0021]

DETAILED DESCRIPTION OF THE INVENTION AND

The embodiments of the present invention will be described below in more detail with reference to Examples and Comparative Examples. Here, "parts" means parts by weight unless otherwise specified.

Comparative Example 1 As shown in Table 2, as a polyol component, 50 parts of a tolylenediamine polyether polyol (OH value: 400) and a shoe-closed polyether polyol (OH value: 45)
0) A mixture of 50 parts with 100 parts of diol, 2.5 parts of water and 25 parts of trichlorofluoromethane as a blowing agent, and 5.5 parts of tetramethylhexamethylenediamine as a catalyst.
Parts, 2 parts of a conventional silicone foam stabilizer A (see Table 1) as a foam stabilizer, and crude M as an isocyanate component
DI (manufactured by Mitsui Toatsu Co., Ltd., trade name: M-300) was blended in a required amount (NCO Index = 1.10) and foamed to obtain a rigid polyurethane foam.

Comparative Examples 2 and 3 Comparative Example 2 had the same formulation as Comparative Example 1 except that 6 parts of water was used as a foaming agent, and Comparative Example 3 contained 6 parts of water as a foaming agent and this foam as a foam stabilizer. Comparative Example 1 except that the silicone foam stabilizer C according to the invention (see Table 1) was used.
It was foamed according to the same formula.

[0024]

[Table 2]

Examples 1-5, Comparative Examples 4-6 Tolylenediamine-based polyether polyol (OH value: 460), ethylenediamine-based polyether polyol (OH value: 500), glycerin-based polyether polyol (OH value: 34) as polyol components ) And dipropylene glycol (OH value 840) were mixed at a predetermined ratio to prepare a mixed polyol component as shown in Table 1. Then, 100 parts of the mixed polyol, 6 parts of water as a foaming agent, 3.0 parts of tetramethylhexamethylenediamine as a catalyst, 2 parts of a silicone foam stabilizer C according to the present invention (see Table 1) as a foam stabilizer, and isocyanate As a component, low viscosity crude MDI (manufactured by Sumitomo Bayer Urethane Co., Ltd., trade name: 44V-10) is used in a required amount (NCO I
ndex = 1.10) Compounded and foamed to obtain a rigid polyurethane foam.

Comparative Examples 7 to 8 Comparative Example 7 is a conventional silicone foam stabilizer A as a foam stabilizer.
Comparative Example 8 was foamed in the same manner as in Example 2 except that Silicone foam stabilizer B (see Table 1) was used.

Next, the physical properties of each rigid polyurethane foam obtained as described above were measured by the following methods. The results are summarized in Table 2.

Free foam density: According to the method specified in JIS A9514. Panel foam density: Foam density (kg / m ³ ) of a panel with face material obtained by foaming at a preheating temperature of 50 ° C. in a mold having an inner size of 400 × 800 × 18 tmm.

Closed cell rate: Measured by a method specified in ASTM D-2856, using a Beckman air-comparison hydrometer for the foam from which the face material has been peeled off. Water absorption: According to the method specified in ASTM D-2127, the water absorption (g / 100 cm ² ) of the above panel with face material after 24 hours is measured.

Dimensional stability: 70 ° C.
, The rate of change of the thickness dimension when left for one week was measured and used as a measure of dimensional stability. However, ○ indicates less than 0.5 mm, Δ indicates 0.5 mm or more and less than 1.0 mm, and X indicates 1.0 mm or more. Adhesion: The peel strength between the face material and the foam was measured for the panel with the face material after foam molding in accordance with the method specified in ASTM D-1623, and this was used as a scale for evaluating the adhesion.
Here, ○ is good at 0.7 kg / cm ² or more, Δ is 0.5 k / cm ²
g / cm ² or more and less than 0.7 kg / cm ² , × indicates less than 0.5 kg / cm ² .

Storage stability: After adjusting the R premix solution, the condition after 3 months at room temperature (20 to 25 ° C.) was observed. O was observed when the solution was uniform, Δ was observed when the solution was somewhat separated, The case of complete separation is indicated by x.

As is evident from Table 2, rigid polyurethane foams (Examples 1 to 5) satisfying all of the above requirements for the polyol component and the foam stabilizer were used even when water was used as the foaming agent. Has a well-balanced foam physical properties (dimensional stability, water absorption, adhesiveness and storage stability) comparable to that of a conventional rigid polyurethane foam (Comparative Example 1) produced as a main foaming agent.

More specifically, in Comparative Example 2, the total amount of the blowing agent of Comparative Example 1 was changed to water.
Dimensional stability and adhesiveness are inferior to those of Therefore, in Comparative Example 3, the silicone foam stabilizer C according to the present invention was combined with the conventional polyol component, but the shrinkage due to water foaming was not suppressed and the result was still lacking in dimensional stability.

Comparative Examples 4 to 6 are examples in which the blending amount of the glycerin-based polyether polyol (c) among the polyol components (a) to (d) is out of the range of the present invention. As can be seen from the above, if the blending amount of the glycerin-based polyether polyol (c) exceeds 25 parts, the closed cell ratio is too low, the water absorption is increased, and the premix liquid is liable to be separated. Storage stability deteriorates. On the other hand, if it is less than 15 parts (Comparative Example 5), the improvement in dimensional stability due to the decrease in the closed cell ratio and the improvement in adhesiveness based on the improvement in flyability cannot be sufficiently achieved.

On the other hand, in Examples 1 to 5 in which the polyol mixture according to claim 1 of the present invention was used as a polyol component, the foam density, dimensional stability, water absorption, adhesiveness, storage stability, etc. The foam properties are improved in a well-balanced manner.

Comparative Examples 7 and 8 are examples in which the conventional silicone foam stabilizer A or B was used in place of the silicone foam stabilizer C in Example 2. If the foam stabilizers are different, even if the polyol component satisfies the requirements of the present invention, no decrease in the closed cell rate is observed, and the object of the present invention cannot be achieved.

[0037]

As described above, according to the present invention, even when water is used alone as a blowing agent, shrinkage at room temperature is small and excellent in dimensional stability, which is as good as that of freon foaming. Is obtained, and a low-density rigid polyurethane foam having sufficient water absorption resistance and storage stability is obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location C08G 101: 00)

Claims (3)

[Claims] 1. A method for producing a rigid polyurethane foam in which a polyol component and an isocyanate component are reacted in the presence of water, a tertiary amine catalyst and a silicone foam stabilizer, wherein (a) tolylenediamine is used as the polyol component. Polyether polyol as initiator (OH number 46
0 ± 20) 10 to 40% by weight, and (b) a polyether polyol (OH number 50)
0 ± 20) 20 to 50% by weight and (c) a polyether polyol having glycerin as an initiator (OH value 34 ± 5)
A mixture of 15 to 25% by weight and (d) 10 to 25% by weight of dipropylene glycol (OH value 840) is used, and the silicone foam stabilizer has an average molecular weight of 5
000 to 10,000, the silicone concentration in the molecule is 40 to 50% by weight, and the EO / PO ratio is 70/30 to 80 /
20. A method for producing a rigid polyurethane foam, comprising using a polyoxyalkylene glycol / dimethylpolysiloxane / block copolymer in the range of 20. 2. The polyol mixture having an average OH value of 4
The method for producing a rigid polyurethane foam according to claim 1, which is in the range of 00 to 500. 3. A polyoxyalkylene glycol / dimethylpolysiloxane / block copolymer obtained by inactivating said silicone foam stabilizer by substituting an active hydrogen terminal group in the molecule with a substituent which is inactive to an isocyanate component. The method for producing a rigid polyurethane foam according to claim 1 or 2, which is a united product.