JPH08157709A - Production of rigid polyurethane foam - Google Patents

Abstract

PURPOSE: To obtain a composition having good storage stability and used for forming a rigid polyurethane foam. CONSTITUTION: This production process is the one comprising reacting a polyol component system with an isocyanate component in the presence of water as a blowing agent, which process comprises previously forming an agitated premix comprising a silica powder composition to be mixed with the polyol component system and a silicone foam stabilizer and mixing this premix with the polyol component system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for producing a rigid polyurethane foam, and more specifically, it uses water that does not destroy the ozone layer at all as a blowing agent to produce a rigid polyurethane foam excellent in room temperature shrinkability and adhesiveness with a face material. The present invention relates to a manufacturing method.

[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 rigid polyurethane foam using only water as a foaming agent has 1) room temperature shrinkability and thermal conductivity remarkably deteriorated as compared with a foam foamed using conventional CFC-11. Problems such as deterioration will occur. As a solution to the problem, the present inventors have disclosed in JP-A-6-192564 a method of producing a rigid polyurethane foam with at least an isocyanate component, a polyol component, and water alone as a foaming agent. 5 parts by weight are added, and in addition, the secondary particle diameter of silica is 1 μ to 10 μ, the pore volume of silica is 1.0 to 5.0 cm ² / g, and the average pore diameter is 3.
It proposes a method for producing a rigid polyurethane foam, which is characterized by having a thickness of 00 to 2000 angstroms.

[0003]

When a rigid polyurethane foam is produced by adding a silica powder composition and using water as a foaming agent, it is possible to prevent the decompression due to the equilibrium of the diffusion and invasion of the foaming gas, and the low density (20 to 20 Even 25 kg / m ³ ) can stop the shrinkage of the foam. However, when the silica powder composition is simply added to the compounded liquid, there is a problem in dispersibility, and the product is separated due to aging and precipitates, resulting in variations in the product of the rigid polyurethane foam, resulting in poor practicality. It is necessary to improve the storage stability of the compounded liquid together with the effect of preventing shrinkage.

[0004]

As a result of earnest research to solve the above problems, the present invention has been achieved. That is, the present invention is a hard reaction obtained by reacting a polyol component and an isocyanate component with water as a blowing agent. In a polyurethane foam, a silica powder composition as a modifying additive is preliminarily stirred and mixed with a silicon foam stabilizer, and 0.5 to 10 parts by weight is added to 100 parts by weight of the polyol. The silicon foam stabilizer to be mixed in advance has a molecular weight of siloxane / oxyalkylene constituting the silicon foam stabilizer of 12000 to 1400.
It is a method for producing a rigid polyurethane foam having a range of 0.

An object of the present invention is 22 kg / m ^{3 to} 25 kg / m ³
That is, it improves cold shrinkage in a low-density foam. Generally, the thickness of the cell membrane of rigid polyurethane foam is about 1 mμ to 10 mμ. 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 powder compositions were examined as porous materials having excellent gas permeability, silica powder compositions obtained by a wet method are 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 composition 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 passage of nitrogen and oxygen in the air over time after foaming. Let To describe the optimum amount and shape of the silica powder composition as a modifying additive, the diameter of secondary particles is preferably 1 μm to 10 μm. 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. The pore volume of the silica powder composition is 1.0 to 5.0 cm ³ / g (average pore diameter 300 to 2
000 angstroms) is preferred. 1.0 cm ³ /
At less than g, room temperature shrinkage occurs, and at more than 5.0 cm ³ / g, the closed cell rate decreases, which is not preferable.

However, the above-mentioned silica powder composition has a drawback that when it is blended with a foaming agent, a foam stabilizer, a catalyst and a flame retardant in a polyol, it separates and precipitates with the passage of time. Separation and precipitation are particularly severe in drum can storage, which guarantees a usable period of 3 months.

The present invention has been achieved as a result of extensive research on a method for preventing separation and precipitation of a silicon powder composition.
The secondary particles of silica aggregates have fine pores between them. When a silica powder composition is used for producing a rigid polyurethane foam, a polyol, a foaming agent, a catalyst, a flame retardant, and a silicone foaming agent are mixed and stirred to form a compounded liquid, there is no problem when used immediately after compounding. However, if it is used several days after the compounding, the change with time is large, and the composition is separated and deposited to deteriorate the room-temperature shrinkability of the foam. In the case of a drum can whose use is guaranteed for 3 months, the silica powder composition separates and precipitates in the drum can, making it unusable. The cause may be that a large amount of low-viscosity polyol or the like in the compounding liquid enters the pores of the silica powder composition, and the role of the pores is impeded, resulting in a mere filler.

The inventors of the present invention have conducted extensive studies in order that the pores of the silica powder composition can maintain good results in foam formation.
It was found that when the silica powder composition was used by mixing it in the silicon foam stabilizer in advance, there was almost no change with time even if it was added to the compounding liquid, and the silica powder did not separate and deposit even when stored in a drum for 3 months. It was As the silicone foam stabilizer, those for rigid polyurethane foam can be used, but those having a molecular weight of 12,000 to 14,000 as a siloxane / oxyalkylene copolymer are preferable.

As the isocyanate component in the present invention, various known polyfunctional aliphatic, alicyclic and aromatic isocyanates can be used. 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), etc. are fisted. The active hydrogen compound having two or more active hydrogen-containing functional groups capable of reacting with an isocyanate group is a hydroxide compound or a mixture of two or more kinds of the compounds. 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 polyamide 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 an initiator such as a polyhydric alcohol, a saccharide, an alkanolamine or the like, particularly an alkylene oxide such as propylene oxide or ethylene oxide is preferable. Also,
As the polyol, it is also possible to use a polyol composition in which fine particles of vinyl polymer are dispersed in a polyether polyol, which is mainly called a polymer polyol or a graft polyol. Polyester 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, Examples include trimethylolpropane, pentaerythritol, diethanolamine and triethanolamine. The hydroxyl value of the polyol or the mixture of active hydrogen compounds is often selected from the range of about 15 to 2000 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, FA-1 from Sanyo Kasei
03T (hydroxyl value 50) Other polyols include
EX-425R (hydroxyl value 420) manufactured by Asahi Glass Co., Ltd. in which propylene oxide is added to sucrose and triethylenediamine is used.

When reacting an active hydrogen compound with a 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 multimerization catalyst for reacting isocyanate groups such as a metal carboxylate is used depending on the purpose. Other optional additives include, for example, fillers, stabilizers, colorants, flame retardants and the like. Typical flame retardants include tris (chloropropyl) and phosphate (TMCPP).

Using these raw materials, polyurethane foam, urethane-modified polyisocyanurate foam, and other foaming synthetic resins can be obtained. The present invention is particularly useful in the production of rigid polyurethane foams, urethane-modified polyisocyanurate foams, and other rigid foams, which is a field in which a large amount of halogenated hydrocarbon-based blowing agents is used. Among them, it is particularly useful in the production of a rigid polyurethane foam obtained by using a polyol having a hydroxyl value of 40 to 900 or a polyol compound and an aromatic polyisocyanate compound.

[0013]

[Function] A silica powder composition is added to a rigid polyurethane foaming undiluted solution containing water alone to foam, to promote the escape of carbon dioxide into the atmosphere and to allow nitrogen and oxygen to permeate through the foam film of the foam after a lapse of time. Since the room temperature shrinkage is prevented and the silica powder composition that dissolves in toluene is mixed and used in the silicon foam stabilizer, the separation and precipitation of the silica powder in the compounding liquid is reduced and the defects are reduced.

[0014]

EXAMPLES The present invention will be described based on examples. The formulations shown in Table 1 were prepared and adjusted to 20 ° C. Among them, the foam stabilizers with * marks in Table 1 indicate that the * marks were preliminarily stirred in each formulation. Weigh in a 500cc death cup so that the total amount is 200g, and use a disk-type peller mixer (rotation speed 700
0) is stirred for 7 seconds, poured into an aluminum mold of 180 × 180 × 150 mm, heated and removed from the mold. The physical properties of the foam are measured after 24 hours. The measuring method is a free foaming density JIS9514 unit kg / m ³ Panel foam density JIS9514 kg / m ³ Compressive Strength ASTM T1621 kg / m ² adhesive ASTM-D1623 Units kg / cm ^2. The cold dimensional stability, the humidity dimensional stability and the storage stability are visually observed. The composition and physical properties are shown in Table 1, and the properties of silicon as a foam stabilizer are as follows. Average molecular weight Silicon concentration (%) EO (%) Silicon A 2000-4000 20-30 100 Silicon B 4000-6000 30-40 100 Silicon C (invention product) 12000-14000 20-30 60-80 Silicon D 4000-6000 20-30 60-80 Silicon E 6000-8000 20-30 100 In addition, EO (%) shows the ratio of EO (ethylene oxide) as oxyalkylene.

[0015]

[Table 1]

[0016]

EFFECT OF THE INVENTION A pre-stirred mixture is prepared in advance with a silica powder composition and a silicon foam stabilizer as a hard polyurethane compounding liquid for water-only foaming, and the pre-stirred mixture is stirred and mixed into a polyol component system, The storage stability of the compounded liquid has been dramatically improved. Moreover, dimensional stability (small shrinkage) as a foamed product is also good.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C08K 5/54 C08L 83/12 LRY // (C08G 18/42 101: 00) (72) Inventor Katsuzo Anraku 1176 Uchigaike, 1-6, Inami-cho, Kako-gun, Hyogo Prefecture Toyo Tire & Rubber Co., Ltd. Hyogo Plant Hyogo Factory

Claims (2)

[Claims] 1. In a rigid polyurethane foam obtained by reacting a polyol component system and an isocyanate component with water as a foaming agent, a silica powder composition to be mixed with a polyol component system is previously stirred with a silicon foam stabilizer before stirring foaming. A method for producing a rigid polyurethane foam, which comprises mixing and preparing a pre-stirred mixture, and mixing the pre-stirred mixture with a polyol component system. 2. A method for producing a rigid polyurethane foam, wherein the silicone foam stabilizer according to claim 1 is a siloxane / oxyalkylene copolymer having a molecular weight of 12,000 to 14,000.