JP6786147B2 - Sealing material made of polyurethane foam with high heat resistance and high water resistance - Google Patents

Description

The present invention relates to a water-stopping sealing material used in the fields of automobiles, houses, construction, and OA equipment, and particularly to a sealing material made of polyurethane foam having excellent heat resistance.

Conventionally, a sealing material made of polyurethane foam has excellent water-stopping properties, and is therefore used in many fields such as automobiles, houses, construction, and OA equipment.
In the early days of polyurethane foam sealants, along with the polyol component and polyisocyanate component, a hydrophobic substance consisting of hydrocarbons such as paraffin, waxes, coal tar, and asphalt was used as a waterproofing agent to impart water stopping properties. Although it has been an essential requirement to include it, waterproofness of hydrocarbons and the like can be achieved by selecting and combining various polyol components and polyisocyanate components, and by adding other foaming agents, foaming agents, catalysts, cross-linking agents, etc. A sealant made of polyurethane foam showing good water resistance was found without the addition of an imparting agent.

A U-shaped water blocking test is used as a method for evaluating water stopping of a polyurethane foam sealant. The U-shaped waterproof test method uses a U-shaped waterproof tester as shown in FIG. 1 and uses two acrylic resin plates (1) of U-shaped test pieces (1) with a thickness of 10 mm and a width of 10 mm. A U-shape is sandwiched between 3) with a spacer so that the compression ratio is 50% of the product thickness, and a predetermined amount of water is injected into the U-shape from above and held for 24 hours. 2), so-called water stoppage pressure and water height were evaluated.
The development of polyurethane foam sealant is aimed at providing high water resistance, low density for weight reduction and low price, and thermal resistance for expansion of use.

For example, Patent Document 1 (Japanese Unexamined Patent Publication No. 2002-338944) states that "a low-density water-stopping polyurethane foam sealing material made of a flexible urethane foam obtained from a polyol, an isocyanate, a foam stabilizer, a cross-linking agent, a catalyst and a foaming agent". A PPG-based polyol is used as the polyol in 100 parts by weight, an MDI-based isocyanate is used in an amount of 60 parts by weight or more as the isocyanate, and an isocyanate or a silicone having a reactive group with the polyol is used as a foam stabilizer as a metal. A catalyst having an active hydrogen that reacts with an isocyanate group is used as a cross-linking agent, and 3 parts by weight or more of water is used as a foaming agent. The density is 45 kg / m ³ or less, and the water stoppage holding time is 24. A low-density water-stopping urethane foam sealant having a water-stopping pressure of 50 mm or more over time. "

Patent Document 2 (Japanese Unexamined Patent Publication No. 2003-193031) states that "a water-resistant polyurethane sealing material composed of a polyester polyol dimerate and an isocyanate and having excellent vibration damping properties, wherein the short-chain diol of the polyester dimerate polyol is a short-chain diol. A water-resistant polyurethane sealant having excellent vibration damping properties, which has no ether bond and has 25% or more of the carbon number of the short-chain diol side chain with respect to the total carbon number of the short-chain diol. " This product has vibration damping properties, low water absorption and low moisture permeability, and improved moisture and heat resistance. Further, Patent Document 3 (Japanese Patent Laid-Open No. 2005-60502 states that "as a polyol, a polyether polyol having an ethylene oxide addition molar ratio of less than 10 mol%, and as an isocyanate compound, tolylene diisocyanate alone or in combination with MDI isocyanate". As a foaming agent, it contains less than 10 mol% of MDI, is an organosilicone compound, has two reactive hydroxyl groups in the side chain, and has a siloxane content of 20 to 30%. , A thin, open-cell, low-density polyurethane foam sealant characterized by the use of water ”has been disclosed, with a density of 32.5 kg / m ^{3 to} 55.4 kg / m ³ and a still water retention time. The water stopping pressure is 5 to 13 cm Aq or more in 24 hours. Further, in Patent Document 4 (Japanese Unexamined Patent Publication No. 2012-57060), "(A) Dimeric polyester polyol 60 to 100% by mass and polyoxypropylene glyceryl ether 40 to" 100 parts by mass of a polyol containing 80% by mass or more of a polyol composed of 0% by mass, (B) an isocyanate compound, (C) a trifunctional cross-linking agent having a trimethylolpropane skeleton, 3 to 6.5 parts by mass, (D) A polyurethane foam containing 1 to 10 parts by mass of a foaming agent and 1 to 10 parts by mass of an (E) foaming agent, and the total active hydrogen in the components (A) and (C) that can react with isocyanate groups. "Polyurethane foam, characterized in that the proportion of the isocyanate group concentration in the component (B) to the group concentration is 80 to 106" is disclosed, and the obtained polyurethane foam according to the description of the patent publication. The density of the compound was 25 to 35 kg / m ³ , and the height of the water after holding for 24 hours was 50 mm or more, and even if the height of the water was 80 mm, there was no water leakage even after holding for 24 hours.
In producing the polyurethane foam sealant in this way, various materials such as a polyol component, an isocyanate component, a foam stabilizer, a foaming agent, and a cross-linking agent are selected as raw materials thereof, and the polyurethane foam is specified while specifying the blending amount thereof. It has been studied to find properties as a sealing material, especially a low density and highly water resistant polyurethane foam sealing material.
When the density of the polyurethane foam sealant currently on the market and the water blocking height by the U-shaped waterproof tester were examined, as shown in FIG. 2, the low density one generally has a low water blocking height. The one with excellent water stopping property had high density.
Further, in the conventional technique, a waterproofing agent such as a hydrocarbon is often added, but since the waterproofing agent does not react, it remains as it is, so that it exists on the surface of the polyurethane resin skeleton and is subjected to adhesive processing. Since the adhesiveness with the adhesive may be deteriorated, there has been a demand for a material that does not contain a waterproofing agent.

In addition, polyurethane foam consists of urethane bonds formed by the reaction of urea groups and hydroxyl groups, but urethane bonds are sensitive to heat and the bonds are broken at 80 ° C to 120 ° C, so they are not suitable for use in high temperature environments. It was. There is a demand for a product that can maintain its physical properties unchanged from those in a normal state even in a high temperature environment.

JP-A-2002-338944 Japanese Patent Application Laid-Open No. 2003-193031 Japanese Patent Application Laid-Open No. 2005-60502 Japanese Unexamined Patent Publication No. 2012-57060

The present inventors have completed the present invention as a result of various studies to obtain a polyurethane foam sealing material having a lower density, higher water stopping property, and higher heat resistance than the above-mentioned commercially available ones. Provided is a sealing material made of a polyurethane foam that does not use a waterproofing agent and has high heat resistance and high water resistance while having a high property property and can be used in a high temperature environment and having a lower density than conventional ones. It is a thing.

The gist of the present invention is a highly heat-resistant and highly water-stopping sealing material composed of a polyurethane foam containing a polyol component, a polyisocyanate compound, a foaming agent and a foam stabilizer as essential components, and the polyol component is an OH-terminal urethane prepolymer. After holding for 600 hours at 150 ° C., which is a mixture of castor oil-based polyols in a ratio of 10:90 to 80:20, the change in air permeability is less than 3 times the original air permeability, and the tensile strength. high heat water stopping resistant sealant change of 50% or less of the original tensile strength it is.

The sealing material according to the present invention has a density of 25 kg / m ³ or less and a water blocking height of 100 mm or more for holding for 24 hours, which is much lower density and higher water stopping property than conventional products, and is a flame retardant. By adding FMVSS No. It clears 302 and has the same adhesive processability as general-purpose polyurethane foam.
In addition, even after holding at 150 ° C. for 600 hours with the same composition, the change in water permeability, in other words, the change in air permeability is 3 times or less of the original air permeability, and the change in tensile strength is 50% or less of the original tensile strength. This is a sealing material having high heat resistance, and the amount of change in the sealing material in terms of mechanical properties such as elongation and tear strength other than tensile strength is extremely small as compared with the conventional one. is there.

U-shaped waterproof test device Schematic diagram of the density of commercially available products and the water stop height of 24-hour holding when measured with a U-shaped water stop test device. The figure which showed the change of the air permeability of the test piece which was left overnight after heat treatment at 150 degreeC for a predetermined time. The figure which showed the change of the tensile strength of the test piece which was left overnight after heat treatment at 150 degreeC for a predetermined time. The figure which showed the change of the elongation rate of the test piece which was left overnight after heat treatment at 150 degreeC for a predetermined time. The figure which showed the change of the tear strength of the test piece which was left overnight after heat treatment at 150 degreeC for a predetermined time.

The polyurethane foam of the present invention contains a polyol component, a polyisocyanate compound, a foaming agent and a defoaming agent as essential components, and each component used in the present invention will be described in detail below.
a. Polyurethane component As the polyol component at the time of producing polyurethane foam, in the present invention, an OH-terminal urethane prepolymer obtained by reacting a castor oil-based polyol and a polyether-based polyol obtained by addition polymerization of an alkylene oxide having 3 or more carbon atoms with isocyanate is used. That is, it is composed of a mixture of an OH-terminal urethane prepolymer and a castor oil-based polyol having a ratio of 10:90 to 80:20, and in particular, an OH-terminal urethane prepolymer using a trifunctional polypropylene polyol having a molecular weight of 3000 and a castor oil-based polyol. The polyol component composed of polyol forms a polyurethane foam showing good water stopping property.
Since urethane prepolymer has a high viscosity, the cells of the produced polyurethane foam become fine. Therefore, it is considered that the gap through which water enters is reduced, which promotes the improvement of water stopping property. The viscosity of the urethane prepolymer is preferably 2000 to 10000 mPa · s (25 ° C.), more preferably 4000 to 6000 mPa · s (25 ° C.).
Further, when the ratio of the OH-terminal urethane prepolymer to the castor oil-based polyol is higher than that of the OH-terminal urethane prepolymer, a polyurethane foam having higher heat resistance can be obtained.
b. Polyisocyanate Compound In the present invention, any of known aliphatic, aromatic, alicyclic, and aromatic-aliphatic polyisocyanates can be used as the polyisocyanate compound. Hexamethylene diisocyanate, 1,4-tetramethylene diisocyanate and the like are used as the aliphatic isocyanate compound, tolylene diisocyanate (TDI) and diphenylmethane diisocyanate (MDI) are used as the aromatic polyisocyanate compound, and the alicyclic polyisocyanate compound is used. Examples include norbonan diisocyanate and water-added diphenylmethane diisocyanate, and examples of aromatic-aliphatic polyisocyanate include xylene diisocyanate and polymethylene polyphenylenediisocyanate. In the present invention, these are used alone or as a mixture.
In particular, the TDI-based isocyanate used in the present invention may be a general-purpose isocyanate, and examples thereof include TDI having an isomer ratio of 2,4 and 2,6 isomers of 80:20. The MDI-based isocyanate may be a general-purpose one, for example, diphenylmethane diisocyanate (MDI), crude MDI, carbodiimide-modified liquid MDI, urethane-modified MDI that has been previously reacted with polyol, and the like. Can be mentioned.

c. Foaming agent As the foaming agent, a known foaming agent used for producing polyurethane foam can be used. For example, water alone or a combination of water and dichloromethane can be mentioned, but in the present invention, water is used alone from the viewpoint of water stopping and environmental problems. The amount of water to be blended is about 1 to 10 parts by mass, preferably 3 to 5 parts by mass with respect to 100 parts by mass of the polyol component (a).
d. Defoaming agent A reactive silicone defoaming agent is used as the defoaming agent. That is, in the present invention, a reactive silicone defoaming agent having a group that reacts with isocyanate is used. As these reactive groups, a hydroxyl group, an amino group, a mercapto group, a carboxyl group, an epoxy group and the like can be considered, but a hydroxyl group and an amino group are particularly preferable because of their ease of reaction. As the reactive silicone defoaming agent, a polydimethylsiloxane-polyalkylene oxide copolymer is typical. An example of this is shown in the chemical formula as follows.

(In the formula, m is the number of dimethylsiloxane, n is the number of side chains, m and n are integers of 1 or more, and a and b are integers of 0 or more.)
As the above-mentioned reactive silicone having a hydroxyl group, a mixture with another reactive silicone having a hydroxyl group, an epoxy group, a carboxy group, a mercapto group and an amino group can also be used. In this case, it is preferable to mix 10% by mass or more of the reactive silicone of the hydroxyl group.
In many foams obtained by using a silicone foam stabilizer having no general-purpose reactive group, the silicone component bleeds out to the resin surface and the compression residual strain is good, but the water-stopping property is not exhibited.

e. Catalyst A catalyst may be used in the production of the polyurethane foam of the present invention. Examples of the catalyst include tertiary amines and metal compounds. These catalysts may be used alone or in combination, but typical compounds include triethylenediamine, triethylamine, n-methylmorpholine, n-ethylmorpholine, 2-dimethylaminoethyl ether, N, N, as tertiary amine catalysts. There are N', N'-tetramethylbutanediamine and the like. These may be used alone or in combination. The tertiary amine catalyst is 2.0 parts by mass or less, preferably 0.3 to 1.9 parts by mass, based on 100 parts by mass of the polyol component.
Preferred metals for the metal catalyst include tin, lead, copper, iron, titanium, zirconium, nickel, bismuth, cobalt, sodium, potassium and zinc. Among them, a preferred metal catalyst is a tin compound, stanas octoate.
f. Flame Retardant The polyurethane foam of the present invention can also impart flame retardancy, and tribromoneopentyl alcohol, dibromoneopentyl glycol, tribromophenol, pentabromobenzyl acrylate, pentabromobenzyl acrylate, hexabromocyclododecane, Bromine-based flame retardants typified by decabromodiphenyl oxide, tetrabromobisphenol A, etc., chlorine-containing phosphate compounds such as trischloroethyl phosphate, trischloroporopyl phosphate, trisdichloropropyl phosphate, and their condensed phosphate esters. A compound, a non-halogen condensed phosphoric acid ester compound, or the like can be used.
When a flame retardant is used, it cannot be added in a large amount because the flame retardant itself tends to reduce the water blocking property. On top of that, FMVSS No. In order to achieve 302, 8 parts by weight or more is preferable with respect to 100 parts by weight of the polyol component.
g. Other Additives Antioxidants for improving heat resistance, additives such as ultraviolet absorbers for improving weather resistance, colorants such as carbon black, fillers such as calcium carbonate, etc. can be arbitrarily used as needed.

Polyurethane foam manufacturing methods include a slab stock method, a casting method such as spray coating or roll coating, a molding method of molding in a mold, a dispenser method of casting from a thin nozzle, and the like, and a method for manufacturing a sealing material according to the present invention. Any method may be used.

The characteristics of the sealing material according to the present invention, in addition to it a low density, air permeability of, 10 mm aeration rate of thickness 10cc ^/ cm 2 ^/ sec or less, preferably in less 2cc ^/ cm 2 ^/ sec .. The 50% compression residual strain is 15% or less, preferably 10% or less. Further, the water-stopping holding time is extended, and stable water-stopping is exhibited for a long period of time. As a method of use, compression is performed so that the compression rate is about 20 to 80%, so that it is preferably desired to maintain water stoppage for a long time at a low compression rate. In particular, depending on the construction conditions, the sealing material is often desired to be soft, and the sealing material according to the present invention can satisfy such a requirement.

Examples showing the present invention in more detail will be described, but the present invention is not limited to these examples.
The compounding agents used in the examples of the present invention are as follows.
-Polyurethane component: OH-terminal urethane prepolymer Synthesized by reacting a polypropylene glycol (PPG) / TDI = 2 mol / 1 mol mixed solution having a molecular weight of 3000 and a number of functional groups of 3 at 80 ° C. for about 2 hours in the presence of a metal catalyst. Polyurethane prepolymer which is a terminal hydroxyl group Hydroxyl value 36.3 Viscosity 5000 mPa · s (25 ° C)
-Polycarbonate component: URIC HF-2050 Silicone oil-based polyester polyol, hydroxyl value 90, manufactured by Ito Oil Co., Ltd.-Polycarbonate component: Actol T-3000S, molecular weight 3000, PPG hydroxyl value with 3 functional groups, 56 Mitsui Chemical Industry SKC, polyurethane company, defoaming Agent: NIAX SILICONE L-636S Reactive Silicone Defoamer Momentive Performance Materials Japan LLC ・ Foaming agent: Water ・ Flame retardant: FYROL A300TB Halogen-containing phosphoric acid ester compound ICL-IP ・ Flame retardant: DG580 Made by Daihachi Chemical Industry Co., Ltd.

・ Amine catalyst: TEDA-L33 Triethylenediamine DPG solution (containing 33%) Made by Toso Co., Ltd. ・ Tin catalyst: Neostan U-28 made by Nitto Kasei Co., Ltd. ・ Pigment: UT BLACK4903 Sanyo Dye Co., Ltd. T-80 Tolylene diisocyanate Mitsui Kagaku SKC Polyurethane Co., Ltd. ・ Water repellent: PW380 NCO index of Idemitsu Kosan Co., Ltd. Isocyanate index Isocyanate group in polyisocyanate compound with respect to total active hydrogen group concentration in polyol compound capable of reacting with isocyanate group Equivalent ratio of concentrations.

The properties of the obtained polyurethane foam were measured by the following method.
-The value was measured by using a Frazier type tester for a foam with a ventilation volume of 10 mm according to the JIS K 6400-7B method.
The upper part is the upper part of the block, and the lower part is the lower part of the block.
-Density Measured according to JIS K 6400-1.
50% hardness In a test according to the JIS K 6400-2 D method, a test piece having a thickness of 50 mm and a size of 100 mm × 100 mm is used to compress the test piece over the entire pressure plate. Pre-compression is performed once at 50%, and the compressive stress after 50% compression in this test and leaving for 20 seconds is determined.
50% compression residual strain According to JIS K6400-4 A method. The compression rate is 50%.
・ FMVSS No. 302 Tested according to the flame retardancy standard for automobile interior materials.
-Water-stopping test result of water-stopping test result at 100 mm (n = 3) n number 3 when compressed by 50%. As described above, using a U-shaped waterproof tester as shown in FIG. 1, a U-shaped test piece having a thickness of 10 mm and a width of 10 mm is placed between two acrylic resin plates to obtain the product thickness. Water was injected into the U-shape from above so that the compression ratio was 50%, and the water stop height was 100 mm. Those that did not leak for 24 hours were marked with "○", and those that leaked within 24 hours were marked with "x". 3H means that water leakage occurred after 3 hours.
-Mechanical strength measurement method after heat aging.
-Tensile strength / elongation A No. 2 test piece described in JIS K 6400-5 was prepared at a thickness of 12.5 mm, heat-treated at 150 ° C. for 100 hours, 286 hours, 500 hours, and 600 hours, and then overnight. With the test piece left standing, the maximum load at break is measured according to JIS K 6400-5, and the elongation at break is measured according to the same standard.
-Tear strength An angle-type test piece described in JIS K 6400-5 was prepared with a thickness of 12.5 mm, heat-treated at 150 ° C. for 100 hours, 286 hours, 500 hours, and 600 hours, and then allowed to stand overnight. With the test piece, measure the maximum load at break according to JIS K 6400-5.

Examples 1-5 and Comparative Examples 1-3
It was poured uniformly into the box, and after reaction curing, a block-shaped polyurethane foam was obtained. The properties of the obtained block-shaped polyurethane foam are added to Table 1.

As is clear from Table 1, when a mixture of OH group-terminated urethane prepolymer and castor oil-based polyol (Example 1) and a mixture of 10:90 (Example 4) were used, the density was 21.9. A polyurethane foam sealant having a low density of 21.7 and a high water-stopping property having extremely good other physical properties was obtained.
On the other hand, when the OH group-terminated urethane prepolymer was not used as the polyol component and only the castor oil-based polyol was used (Comparative Example 1), good water stopping property was exhibited, but compared with the case where the OH group-terminated urethane prepolymer was used in combination. Therefore, the 50% compression residual strain is very large and there is a risk of water leakage over time, so it cannot be said that the material has good physical properties. Further, when a 50:50 mixture of polypropylene glycol having a molecular weight of 3000 and castor oil-based polyol was used (Comparative Example 2), the density was higher than that of Example 1 and water leakage occurred. When a mixture of 70:30 was used (Comparative Example 3), water leakage occurred 3 hours after the start of the water stopping test.

Example 6 to Example 10
The compounding agents and compounding amounts shown in Table 2 were uniformly mixed to obtain a block-shaped polyurethane foam having a size of 250 mm × 250 mm × 250 mm by the same method as in the above example. The NCO index at this time was 103.2.
The properties of the obtained block-shaped polyurethane foam are added in Table 2.

As is clear from Table 2, when the amount of the flame retardant added is 7 parts by mass or less, FMVSS No. Although it failed in the judgment of 302, it could be self-extinguished by adding 8 parts by mass. All other properties are good, with a low density of 24 kg / m ³ or less and high water resistance.

Comparative Example 4, Comparative Example 5, Example 11, Example 12
The compounding agents and compounding amounts shown in Table 3 were uniformly mixed to obtain a block-shaped polyurethane foam having a size of 250 mm × 250 mm × 250 mm by the same method as in the above example. The properties of the obtained polyurethane foam are added in Table 3.

Next, the air permeability and mechanical strength of heat aging were measured for the products of Examples 11 and 12 and Comparative Examples 4 and 5. The measuring method was kept at a temperature of 150 ° C. for 0 to 600 hours, and the rate of change was measured. The mechanical tests performed were a tensile strength test, an elongation test and a tear strength test, and the results are shown in Tables 4, 5 and 6.

These results are illustrated as FIGS. 3 to 6.
As apparent from these, the case of using a mixture of OH group-terminated urethane prepolymer and castor oil-based polyol, the physical properties change width after heat aging with showing a low density of density 20 kg / m ³ and 30kg / m ³ A small polyurethane foam was obtained.

The present invention is suitable for use in a high temperature environment even though it is a polyurethane foam by using a mixture of an OH-terminal urethane prepolymer and a castor oil-based polyol in producing a polyurethane foam sealant, and has an extremely low density. It is industrially useful because it was possible to obtain a sealing material with high water resistance.

1 Test piece 2 Water stop height 3 Acrylic resin plate 1 to 8 in Fig. 2 indicate commercially available products.
Each point in FIGS. 3 to 6 is as follows.
◎ Example 12
〇 Example 11
● Comparative example 5
× Comparative example 4

Claims (4)

A highly heat-resistant, highly water-stopping sealant made of polyurethane foam containing a polyol component, a polyisocyanate compound, a foaming agent and a foam stabilizer as essential components, and the ratio of OH-terminal urethane prepolymer to castor oil-based polyol as the polyol component. The change in air permeability is less than 3 times the original air permeability after holding at 150 ° C. for 600 hours, which is a mixture of 10:90 to 80:20, and the change in tensile strength is the original tension. A highly heat-resistant and water-stopping sealing material with a strength of 50% or less. The highly heat-resistant and water-stopping sealing material according to claim 1, wherein the OH-terminal urethane prepolymer uses a trifunctional polypropylene polyol having a molecular weight of 3000. The highly heat-resistant and water-stopping sealing material according to claim 1 or 2, wherein at least a part of the defoaming agent is a reactive defoaming agent containing a hydroxyl group. The highly heat-resistant and water-stopping sealing material according to any one of claims 1 to 3, further adding a flame retardant.

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