JPH06192564A - Production of rigid polyurethane foam - Google Patents

Abstract

PURPOSE:To prevent shrinkage at ordinary temperature and simultaneously improve the adhesiveness in expanding a rigid polyurethane foam with water alone. CONSTITUTION:Silica powder in an amount of 0.5-5 pts.wt. as a modifying additive is added to an expandable stock solution of a rigid polyurethane using water alone.

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 uses water as a foaming agent and has excellent room temperature shrinkability and adhesiveness to a face material. It is a thing.

[0002]

2. Description of the Related Art Conventionally, trichlorofluoromethane (hereinafter abbreviated as CFC-11) as a foaming agent has been used as a method for producing a rigid polyurethane foam having excellent heat insulating properties.
The method of using is known. However, the reduction and elimination of CFCs (including CFC-11), which is one of the causes of ozone layer depletion that has become a problem as environmental destruction, is about to be implemented. Therefore, the foaming of water alone is drawing attention.

However, a polyether polyol having bropyrene glycol, trimethylolpropane, glycerin, ethylenediamine, tolylenediamine, pentaerythritol, methylglucoside, sorbitol, sucrose as an initiator is used as a polyol, using only water as a foaming agent. When used, compared to a foam foamed using conventional CFC-11, the following problems occur: (a) Room temperature shrinkage, thermal conductivity, etc. are significantly deteriorated, and (2) Adhesion with face material is deteriorated. .

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a rigid polyurethane foam which does not impair excellent dimensional stability and adhesiveness with a face material even when water alone is used as a foaming agent. To provide.

[0005]

According to the present invention, 0.5 to 5 parts by weight of silica is added as a modifying additive in a method for producing a rigid polyurethane foam by using at least an isocyanate component, a polyol component and water alone as a foaming agent. A method for producing a rigid polyurethane foam characterized in that the secondary particle diameter of silica is 1 μ to 10 μ, the pore volume of silica is 1.0 to 5.0 cm ³ / g, and the average pore diameter is 300. It is a method for producing a rigid polyurethane foam, which is characterized in that it is ˜2000Å.

The background of using silica in the present invention will be described. Generally, a cell membrane of rigid polyurethane foam has a property of a semipermeable membrane, and the permeation rate varies depending on the type of gas. In the case of water-only foaming, carbon dioxide gas is large in the diffusion from the cell of rigid polyurethane foam, and the invasion rate of air (nitrogen, oxygen) from the outside is delayed, so it is hard due to the decompression at the initial stage of foaming (one week to one month). Polyurethane foams show a tendency to shrink.

Stoichiometrically, carbon dioxide is generated in water foaming of a rigid polyurethane foam at a very high rate of escape into the atmosphere through a bubble film of closed cells. When the gas dissipation rate of conventional trichloromonofluoromethane is set to 1, the carbon dioxide gas is 240 times, while the speed at which the air in the atmosphere penetrates through the cell membrane of closed cells of rigid polyurethane foam is Nitrogen is 30 times and oxygen is 60 times, which is gentle, and the internal pressure in the closed bubbles is rapidly reduced and contracts. In order to prevent shrinkage, a method of increasing the resin portion forming the skeleton portion of the rigid polyurethane foam is conceivable. That is, a method of increasing the apparent density of the foam to increase the skeleton strength is to increase the weight of the heat insulator There was the difficulty of rising costs. Separately, in order to keep the skeletal strength of the rigid polyurethane foam strong, a sucrose-based hydroxyl value of 400 or more is used as the high-functional polyol, and tolylenediamine, triethanolamine, and ethylenediamine are used as the polyols that enhance the reaction degree. , Apparent density 30kg /
At m ³ or more, it was considered that the room temperature shrinkage was 2% or less.

On the other hand, the adhesiveness with the structural material (face material) is an important factor. A low-functional polyol having a hydroxyl value of 400 or less is preferable as the polyol for improving the adhesiveness, but the adhesion and the improvement in the room temperature shrinkage have a contradictory relationship. The object of the present invention is 22 kg / m ^{3 to} 25 kg.
In the low density range of / m ³ , the room temperature shrinkage is improved. Generally, the thickness of the cell membrane of rigid polyurethane foam is about 1 μm to 10 μm. The present invention has been achieved as a result of intensive studies on a modifying additive having good compatibility with a hard polyurethane resin and excellent gas permeability. That is, when various hydrophobic silica powders were examined as porous materials having excellent gas permeability, silica powder obtained by a wet method is advantageous in terms of compatibility. In the wet method, the single particle diameter can be freely made within the range of 1 mμ to 100 mμ, and the shape of the secondary particles in which the single particles are aggregated can be freely made. Secondary particles of silica powder are suitable as modifying additives to the rigid polyurethane foam. Considering from the results of the examination, the secondary particles have fine pores between the particles, promote the passage of carbon dioxide gas into the air during foaming, and smooth the permeation of nitrogen and oxygen in the air over time after foaming. Let The optimum amount and shape of silica powder as a modifying additive is as follows.
μ to 10 μ is desirable. At 1 μm or less, room temperature shrinkage occurs.
When it is 10 μm or more, the closed cell rate is lowered and the thermal conductivity is lowered. Speaking of the pore volume of silica powder, 1.0-
5.0 cm ³ / g (average pore size 300 to 2000 Å) is suitable. If it is 1.0 cm ³ / g or less, room temperature shrinkage occurs, and if it is 5.0 cm ³ / g or more, the closed cell ratio is lowered, which is not preferable.

In the present invention, various well-known polyfunctional aliphatic, alicyclic and aromatic isocyanates can be used as the isocyanate component. For example, hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), 4,4- Dicyclohexylmethane diisocyanate (HMDI), 2,4-tolylene diisocyanate (2,4-TDI), 2,6-tolylene diisocyanate (2,6-TDI), 4,4-diphenylmethane diisocyanate (MDI), orthotoluidine diisocyanate (TODI), naphthylene diisocyanate (NDI), xylylene diisocyanate (XD)
I), lysine diisocyanate (LDI) and the like.

The active hydrogen compound having two or more active hydrogen-containing functional groups capable of reacting with an isocyanate group is a compound having two or more active hydrogen-containing functional groups such as a hydroxyl group and an amino group, or a mixture of two or more kinds of the compounds. Is. In particular, a compound having two or more hydroxyl groups, a mixture thereof, or a mixture containing the compound as a main component and further containing polyamine or the like is preferable. Examples of the compound having two or more hydroxyl groups include polyols such as polyether polyols, polyester polyols, polyhydric alcohols, and hydroxyl group-containing diethylene polymers. In particular, it is preferable to use only one or more polyether polyols or to use them in combination with polyester polyols, polyhydric alcohols, polyamines, alkanolamines and other active hydrogen compounds. As the polyether-based polyol, a polyether-based polyol obtained by adding a cyclic ether to a polyhydric alcohol, a saccharide, an alkanolamine, or another initiator, particularly an alkylene oxide such as propylene oxide or ethylene oxide is preferable. Further, as the polyol, it is also possible to use a polyol composition, which is called a polymer polyol or a graft polyol, in which fine particles of vinyl polymer are dispersed mainly in a polyether polyol. Polyester-based polyols include polyhydric alcohols, polyhydric carboxylic acid condensation-based polyols, and cyclic ester ring-opening polymer-based polyols, and polyhydric alcohols include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, glycerin, and triglyceride. Examples include methylolpropane, pentaerythritol, diethanolamine, and triethanolamine. The hydroxyl value of the polyol or the mixture of active hydrogen compounds is about 15 to 2
It is often selected from 000 according to the purpose.

As a commercially available product, a polyether polyol obtained by adding propylene oxide to sucrose, for example, GR-35 (hydroxyl value 40 by Takeda Pharmaceutical Co., Ltd.).
0), a polyether polyol obtained by adding propylene oxide to toluenediamine, for example, NT-400 (hydroxyl value 400) manufactured by Mitsui Toatsu Co., a polyether polyol obtained by adding propylene oxide and ethylene oxide to glycerin, For example, Sanyo Chemical FA-
103T (hydroxyl value 50) and other polyols include EX-425R manufactured by Asahi Glass Co., Ltd. in which propylene oxide is added to sucrose and triethylenediamine.
(Hydroxyl value 420).

When reacting the active hydrogen compound and the polyisocyanate compound, it is usually necessary to use a catalyst. As the catalyst, a metal compound catalyst such as an organotin compound or a tertiary amine catalyst such as triethylenediamine that accelerates the reaction between the active hydrogen-containing group and the isocyanate group is used. In addition, tetramethylhexamethylenediamine (TM
HMDA), pentamethyldiethylenetriamine, dimethylcyclohexylamine (DMCHA) and the like.
Further, a polymerization catalyst for reacting isocyanate groups such as carboxylic acid metal salts is used depending on the purpose. Further, foam stabilizers for forming good bubbles are often used. Examples of the foam stabilizer include a silicone type foam stabilizer and a fluorine-containing compound type foam stabilizer. Other optional additives include fillers, stabilizers, colorants, flame retardants and the like. Typical flame retardants include tris (chloropropyl) phosphate (TM)
CPP).

By using these raw materials, polyurethane foam, urethane-modified polyisocyanurate foam and other foaming synthetic resins can be obtained. Polyurethane foam is roughly classified into rigid polyurethane foam, semi-rigid polyurethane foam, and flexible polyurethane foam. The present invention is particularly useful in the production of rigid polyurethane foams, urethane-modified polyisocyanurate foams, and other rigid foams, which are fields in which the amount of halogenated hydrocarbon-based blowing agent used is large. Among them, the hydroxyl value is about 4
It is particularly useful in the production of rigid polyurethane foam obtained by using a polyol of 0 to 900 or a polyol compound and an aromatic polyisocyanate compound.

[0014]

[Function] Silica powder is added to a rigid polyurethane foaming stock solution containing water alone to foam, to promote the escape of carbon dioxide into the atmosphere and, after passage of time, allow nitrogen and oxygen to permeate through the foam film of the foam at room temperature. Prevents shrinkage and ensures good adhesion to face materials.

[0015]

EXAMPLES The present invention will be described based on examples. 200g of P liquid + R liquid which prepared the composition of Table 1 and was adjusted to 20 ° C.
To a 500 cc death cup and stirred for 7 seconds with a disk-type propeller mixer (rotation speed 7000).
Pour into an aluminum mold of 0x180x150mm,
Remove from the mold after heating. The physical properties of the foam are measured after 24 hours. Free foam density JIS9514 Unit k
g / m ³ closed cell content ASTM-D2856 Units% cold shrinkage internal standards units% adhesion ASTM-D1623 units k
g / cm ² GR-35 manufactured by Takeda Pharmaceutical Co., Ltd. polyol hydroxyl value 400 NT-400 manufactured by Mitsui Toatsu Co., Ltd. polyol hydroxyl value 400 NC400 manufactured by Mitsui Toatsu Co., Ltd. polyol hydroxyl value 400 DA401 Mitsui Toatsu (stock) ) Polyol hydroxyl value 400 FA-103 Sanyo Kasei Co., Ltd. polyol hydroxyl value 50 TMCPP Daihachi Chemical Co., Ltd. flame retardant SH193 Toray Silicon Co. foam stabilizer Dabco Air Product Co. triethylenediamine silica powder SS-50F Japan Silica Industry Co., Ltd.
Silica Powder Silica Powder SS-165 Nippon Silica Industry Co., Ltd.
Silica powder CR-200 Mitsui Toatsu Co., Ltd. Crude MDI

[Table 1]

[0016]

EFFECTS OF THE INVENTION 0.5 to 5 parts of silica powder is added to a rigid polyurethane foaming stock solution of water-only foaming to obtain a rigid polyurethane foam having room temperature shrinkage of 2% or less after 7 days and 30 days and having good adhesiveness. I was able to get it.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ogi Ogi 1176 Uchigaike, 6th character, Inami-cho, Kako-gun, Hyogo Prefecture Toyo Tire & Rubber Co., Ltd., Hyogo Plant, Hyogo Plant (72) Inventor, Katsuzo Anraku Hyogo 1176, Uchigaike, Inami-cho, Kako-gun 1176, Toyo Tire & Rubber Co., Ltd. Hyogo Plant, Hyogo Factory

Claims (3)

[Claims] 1. A rigid polyurethane foam obtained by reacting a polyol component and an isocyanate component with water as a foaming agent, silica of 0.5 to 5 as a modifying additive.
A method for producing a rigid polyurethane foam, characterized in that it is added in parts by weight. 2. The method for producing a rigid polyurethane foam according to claim 1, wherein the secondary particle diameter of silica is 1 μm to 10 μm. 3. The pore volume of silica is 1.0 to 5.0 cm.
^The method for producing a rigid polyurethane foam according to claim 1 or 2, wherein the average pore diameter at ³ / g is 300 to 2000Å.