JP2002226829A - Polyurethane foam sealing material having high water- impervious performance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyurethane foam sealing material achieving high water- stopping performance with a urethane foam produced by using a PPG polyol to attain the cost merit, freedom of formulation and freedom of functions in place of using a special raw material system or particular filler or additive for improving the water-impervious performance. SOLUTION: The urethane foam sealing material having high water- impervious performance is a flexible urethane foam produced from a polyol, an isocyanate and a foaming agent. The foam is produced by using a PPG polyol as the polyol, an MDI isocyanate as the isocyanate, a silicone having a group reactive with isocyanate or polyol as a foam stabilizer, a compound having active hydrogen reactive with isocyanate group as a crosslinking agent and water as the foaming agent. The foam has a density of >=35 kg/m3 and a water-impervious pressure of >=50 mm at a water-impervious time of 24 hr.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-sealing sealing material used in the fields of automobiles, houses, buildings, and civil engineering, and more particularly to a polyurethane foam-based foam sealing material using a polyether-based polyol.

[0002]

2. Description of the Related Art Conventionally, polyurethane foam has been used as a waterproof sealing material used in the fields of automobiles, houses, buildings and civil engineering. For example, Japanese Patent Publication No. 59-3
Japanese Patent No. 7036 discloses a polyurethane foam using a polyether polyol or a polyester polyol or a mixture thereof obtained by addition-polymerizing an alkylene oxide having 3 or more carbon atoms as a polyol component in an amount of 90 mol% or more, and comprises paraffin, waxes, coal tar, and the like. It is an essential requirement to contain a substance made of hydrocarbon such as asphalt. However, the contact angle of the sealing material with water was 75 degrees or more and the air permeability at a thickness of 10 mm was 10 cc / cm ² / sec or less. A material having a large contact angle or a small air permeability has been required. The contact angle with water can be determined by sandwiching a 10 mm thick polyurethane foam between aluminum foils at a temperature of 180 ° C to 200 ° C.
A value obtained by pressing a film at a temperature of 40 ° C. and a pressure of 40 to 50 kg / cm ² to form a film and measuring it with a contact angle meter. The contact angle meter was measured using a Kyowa contact angle meter CA-A type. The air permeability at a thickness of 10 mm refers to a 10 mm thick foam measured according to the JIS-Flange method of a woven fabric air permeability test. A value measured according to L-1004,
As a device, a breathability tester No. manufactured by Tokyo Seiki Co., Ltd. was used. 8-6
Measured using -9.

For example, Japanese Patent Publication No. 2-55470 discloses that 90 mol% of a polybutadiene-based polyol, a dimer acid-based polyol, a castor oil-based polyol and an alkylene oxide having 3 or more carbon atoms are used as polyol components.
Using at least one selected from the group consisting of the addition-polymerized polyether polyols, as a foam stabilizer, a soft or semi-rigid open-cell polyurethane foam sealing material made of a polyurethane foam using a hydroxyl group-containing organosilicon compound. Has been disclosed. The polyurethane foam sealing material had a 10 mm thickness air permeability of 20 cc / cm ² / sec or less. In Japanese Patent Publication No. 38521/1989, an organosilicon compound based on a polydialkylcycloxane having a primary or secondary amino group is used as a foam stabilizer.
The ratio of polyol to polyisocyanate is NCO / OH
= 0.9-1.3 to produce a soft or semi-rigid open cell polyurethane foam sealant. The air permeability of this polyurethane foam sealing material having a thickness of 10 mm is 100 cc / cm ² /
sec. or less, and Japanese Patent Publication No. 60-49239 discloses a soft or semi-rigid compound obtained from a polyol containing dimer acid or castor oil derivative polyol or castor oil or a mixture thereof as a main component, and a polyisocyanate compound. continuous and foaming of the polyurethane foam sealant is disclosed, air permeability at 10mm thickness of the sealant 60 cc / cm ² /
sec or less.

As described above, in order to obtain a urethane foam sealing material using a polypropylene glycol compound as a polyol component (referred to as a PPG urethane foam sealing material), a hydrocarbon substance is added as a waterproofing agent, and the contact angle is reduced. A water-stop foam was obtained by adjusting the value to a predetermined value. However, the water stop pressure was as low as about 10 mm to about 20 mm, and at most about 50 mm. Further, the water stoppage holding time was as short as about 1 to 2 hours. In addition, the use of a silicone foam stabilizer having a reactive group has been used to improve the water stopping performance. However, in this case, a foam sealing material having a low water stopping pressure and a short water holding time can be obtained with a PPG-based polyol. Had not been. As described above, it has been extremely difficult to improve the water stopping performance using a PPG-based polyol.

On the other hand, the main raw material is a highly hydrophobic polyol,
For example, butadiene polyol, dimer acid ester,
It is known that a high water stop pressure can be obtained by using a special raw material such as castor oil-based polyol (Japanese Patent Publication No. 60-49239), but these are special raw materials such as strength, elongation, and hardness. The degree of freedom of the raw materials is too small to freely change the physical properties. In addition, since the raw material is special, there is also a problem in economics. If the raw material is further reformed, the cost is further increased and the flexibility of the product is reduced.

[0006]

SUMMARY OF THE INVENTION The object of the present invention is not to use a special raw material system or to use special fillers and additives to improve the water stoppage as described above. Another object of the present invention is to provide a urethane foam sealing material (hereinafter, abbreviated as a foam sealing material) which achieves high water stopping performance by using a urethane foam using a PPG-based polyol to obtain a degree of functional freedom.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is to provide a highly water-resistant polyurethane foam sealing made of a flexible urethane foam obtained from a polyol, an isocyanate, a foam stabilizer, a crosslinking agent and a foaming agent. Based on 100 parts by weight of the system polyol, at least 42 parts by weight of an MDI isocyanate as an isocyanate, and further, a silicone having a group reactive with isocyanate or polyol as a foam stabilizer, and an active hydrogen which reacts with an isocyanate group as a crosslinking agent. (Hereinafter referred to as a cross-linking agent) and using water as a foaming agent, a foam sealing material having a high water-stop pressure could be obtained. That is, the gist of the present invention is a highly water-resistant polyurethane foam sealing made of a flexible urethane foam obtained from a polyol, an isocyanate, a foam stabilizer, a cross-linking agent and a foaming agent, wherein 100 parts by weight of a PPG-based polyol is used as the polyol. , with MDI-based isocyanate 42 parts by weight or more as an isocyanate, further and using a crosslinking agent, the use of water at a density 35 kg / m ³ or more, wherein as the blowing agent, water stopping performance waterproofing retention time 24 It is a high water-stop polyurethane foam sealing material having a water stop pressure of 50 mm or more in time.
In the present invention, diphenylmethane diisocyanate (MDI) is used as the isocyanate. Although it has been speculated to some extent that the use of an MDI-based isocyanate enhances the water stopping performance, the present invention has succeeded in greatly improving the water stopping performance by determining the number of parts used. In the present invention, it has been found that by using water and a crosslinking agent together as a foaming agent and using a certain amount or more of an MDI-based isocyanate, the water stopping performance is greatly improved.
It is highly anticipated that a combination of such a polyol, isocyanate and a cross-linking agent will provide a polyurethane foam sealing having a water-stopping property equivalent to or higher than that of a urethane foam using a special polyol such as a dimer acid ester which has been conventionally used. It was not done.

[0008]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail.
The MDI isocyanate used in the present invention may be a general-purpose one, such as diphenylmethane diisocyanate (MD
I), crude MDI, carbodiimide-modified liquid MD
Examples include those referred to as I, those referred to as urethane-modified MDI pre-reacted with a polyol, and those blended with other isocyanates such as tolylene diisocyanate (TDI). The amount of the isocyanate to be used may be an active hydrogen compound such as a polyol or water as a foaming agent or a cross-linking agent, and may be added in accordance with an equivalent amount. Usually, the NCO / OH ratio is preferably about 0.8 to 1.3.
Further, the number of parts by weight of the MDI used should be at least 42 parts per 100 parts of the polyol.

In the present invention, a PPG-based polyol is used. The PPG-based polyol may be a general-purpose one, for example, one having about 2 to 8 functional groups and an OH value of about 20 to 200 can be used. For example, glycerin is typically polymerized by addition polymerization of PO (propylene oxide) and EO (ethylene oxide). EO has an addition molar ratio of 0 to 20%, and may be copolymerized with PO at random in the molecule, or at the terminal (chip) or in the middle (balance). Conventionally, even with PPG-based polyols, ethylene oxide (E
O) It is known that if the added mole ratio is less than 10%, a hydrocarbon substance is added as a waterproofing agent, and if the contact angle is set to a predetermined value, a water-stopping urethane foam can be formed. (For example, see Japanese Patent Publication No. 59-37036). It is well known that ethylene oxide (EO) has high hydrophilicity, and it is generally understood that the higher the EO content, the lower the water stoppage. However, in the present invention, even if the EO addition mole ratio is increased to 20%, the water stoppage can be exhibited. It is not known at all that the water stopping performance is high even if the EO content is high. The fact that water stoppage can be exhibited even when the EO content is high means that the foam has a small cell size and a small pore size because the reaction speed of the MDI-based isocyanate is high when producing a foam. For example, the number of cells of the product of the present invention using an MDI-based isocyanate as an isocyanate component is 20/4 mm or more, which is an extremely fine cell, whereas the cell using tolylene diisocyanate has a low cell number. , Coarse.

Further, when the EO content is high, the curing temperature can be lowered, the curing time can be shortened even if the thickness of the foamed product is small, and the hardness can be reduced. The preferable range of the EO content is 3 to 15%. In this range, the water stoppage is almost the same as when the EO content is low, but rather, it has advantages such as high reaction speed and softness. The molecular weight of the PPG-based polyol used in the present invention is 130
It is preferably 0 or more, and most preferably 1500 or more. P
It is preferable to increase the molecular weight of the PG-based polyol in order to improve the drawbacks of elongation and strength reduction of the foam using the MDI-based isocyanate. As the alkylene oxide that can be added, butylene oxide, phenylene oxide and the like can also be used. Further, a polymer-dispersed polyol obtained by radically polymerizing an unsaturated monomer such as styrene or acrylonitrile in the polyol, which is referred to as a polymer polyol, may also be used. In the present invention, other polyols such as a polyester polyol, a dimer acid-based polyol, and a polyoxyethylene polyol can be added to the PPG-based polyol as long as the function of the present invention is not impaired.

In the present invention, it is necessary to use a silicone foam stabilizer having a group which reacts with isocyanate or polyol. 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. Particularly, a hydroxyl group and an amino group are preferable because of easy reaction. The molecular structure of the silicone foam stabilizer may be a known one, but a typical example thereof is a polydimethylsiloxane-polyalkylene oxide copolymer. The molecular weight of these silicone compounds is about 5,000 to tens of thousands, and the content of the siloxane moiety in the molecule is about 5 to 50%. It is preferable that a reactive group such as a hydroxyl group and an amino group be contained in the polyalkylene oxide.

The essential components of the present invention are a polyol, an MDI-based isocyanate, a reactive silicone, a cross-linking agent and a foaming agent. If any of these is missing, a foam sealing material having a high water-stop pressure cannot be obtained. For catalysts, MD
The use of an organometallic catalyst in the production of a cushion foam with an I-based isocyanate has been avoided from using an organometallic catalyst because the foaming property deteriorates. However, the use of an organometallic catalyst is preferred for improving the water stoppage of the foamed sealing material of the present invention. Examples of the catalyst include a tertiary amine and an organometallic compound. These catalysts may be used alone or in combination. Representative compounds include tertiary amine catalysts such as triethylenediamine, triethylamine, n-methylmorpholine, n-ethylmorpholine, N, N, N ', N'-tetramethylbutanediamine, and the like. Preferred metals of the organometallic catalyst include tin, lead, copper, iron, titanium, zirconium, nickel, bismuth, cobalt, sodium, potassium,
Zinc and the like are preferable, and more preferable organometallic catalysts include stannous octenoate and stannic dibutyl laurate, which are organotin compounds. However, it is not limited to this.

[0013] The conventional contact angle, which represents the water stopping performance, represents the hydrophobicity of the material. On a certain surface, the surface condition of the foam is measured, but the contact angle of the foam material is measured. It is hard to say that the value is accurate because it is hot pressed to smooth the rough surface. In the present invention, the measurement is performed using a U-shaped still water test device (see FIG. 1) described later.

[0014] Conventionally, hydrocarbons have been added as a waterproofing agent in order to enhance the water stoppage. As hydrocarbons, solid resins having a melting point of about 100 ° C., petroleum waxes, ester waxes, tackifiers such as rosin and terpene resins, polybutenes, process oils, are referred to as petroleum resins obtained by polymerizing C4 to C9 fractions. And liquid oils such as phthalic acid esters. In the present invention, these substances may be added, but a foam sealing material having a high static pressure can be obtained without adding these substances. It has never been known that a high water-stopping property can be exhibited without adding such hydrocarbons. The fact that high waterproofness can be exhibited without adding a waterproofing agent in this way not only has many advantages such as the necessity of the raw material tank and the trouble of compounding at the time of manufacturing, but also the effect of the sealing agent from the waterproofing agent. Bleeding, gas, etc., can be prevented, and for example, the cause of fogging, which is a problem in automobiles, can be prevented. Furthermore, the use of such a waterproofing agent slows down the reaction speed of the polyurethane, lowers productivity, and deteriorates restorability. Furthermore, since the foam sealing material is often attached using an adhesive tape, not using such a waterproofing agent leads to an increase in the adhesiveness between the adhesive tape and the foam material.

In the present invention, a low-boiling solvent such as dichloromethane, a fluorine-containing low-boiling solvent or pentane may be used as a foaming agent. However, water which reacts with isocyanate to generate carbon dioxide gas is most preferable because the water-stopping property is enhanced most. In addition, a method of mechanically mixing air, nitrogen, or the like in the raw material is also included.

In the present invention, a polyhydric alcohol having an active hydrogen that reacts with an isocyanate group, a diamine, an amino alcohol, or the like is used as a cross-linking agent. In order to satisfy the softness and elongation of the properties, it is preferable to use a polyhydric alcohol among the crosslinking agents.
Polyhydric alcohols have 2 to 4 functional groups and a hydroxyl value of 60
A polyhydric alcohol of 0 mgKOH / g or more is preferred. In particular, glycol having a functional group of 2 (including an alkylene oxide adduct) is excellent in foaming stability and softness. As typical examples, polyhydric alcohols include ethylene glycol,
Examples include glycerin and trimethylolpropane, and examples of diamines include diphenylmethanediamine, m-phenylenediamine, and 3,3′dichloro-4,4′-diaminophenylmethane. Examples of the amino alcohol include diethanolamine and triethanolamine.

Further, an anti-aging agent for improving heat resistance, an additive such as an ultraviolet absorber for improving weather resistance, a coloring agent such as carbon black, a filler such as calcium carbonate, and the like can be used. The mixing method of the polyurethane foam may be a commonly used one-shot method, prepolymer method, or kwaji prepolymer method.

The method for producing a foam is a slabstock method,
There are a casting method such as spray coating or roll coating, a molding method in a mold, and a dispenser method for casting from a thin nozzle. However, in the present invention, it is preferable to have a self-skin layer on at least one surface. The self-skin layer is formed by a method of applying, supporting, or sandwiching a reaction raw material in each manufacturing method. This self-skin layer increases the adhesion on the water-stop surface as compared with the cell-only foam, and naturally leads to an improvement in the water-stop performance. A method of attaching an alternative to a skin layer such as an adhesive tape on the cell surface in a later step has the same effect as forming a self-skin layer.

[0019]

Examples and Comparative Examples Next, the present invention will be specifically described with reference to examples. The contact angle with water shown in the examples was measured by the method described above, and the water stoppage was measured using a U-shaped water stoppage test device as shown in FIG. That is, a test piece having a size of 10 mm × 10 mm × 300 mm is sandwiched in a U-shape between two acrylic resin plates with a spacer interposed therebetween so as to have a compression ratio of 50% of the product thickness. Water was injected into the vessel so that a predetermined water pressure was obtained. The water stoppage height (mm) indicates a water pressure height at which water does not leak for 24 hours. Example 1 Glycerin was subjected to addition polymerization of propylene oxide (PO) or ethylene oxide (EO) with a molecular weight of 5000, E
O-mol% about 15% of polyol A 100 parts and low molecular weight diol ethylene glycol (EG)
The MDI-based isocyanate was changed by changing from 5 parts to 5 parts. 1.5 parts of water and Da as a catalyst
bco33LV 0.2 part (Sankyo Air Products Co., Ltd. amine-based catalyst) and stannas octate (organic tin compound catalyst) 0.2-0.4 parts, foam stabilizer is polydimethylsiloxane-polyalkylene ether graft copolymer Having a siloxane content of about 20% and a molecular weight of about 8000, and having a polyether terminal of an -OH group (Silicone A)
Was used, and a carbodiimide-modified liquid MDI of MDI (NCO% = 29%) was used as an isocyanate to form a foam. Table 1 shows the physical properties and waterproofness of the obtained foam. FIG. 2 shows the relationship between the water blocking property and the number of isocyanate parts used.

[0020]

[Table 1]

From the results shown in Table 1 and FIG.
Although the water blocking property is 5%, the water stopping performance starts to be as high as 60 mm when the number of MDI-based isocyanate parts exceeds about 40 parts. Preferably, the high water-stop performance is maintained when the number of MDI-based isocyanate parts is about 45 parts or more, and more preferably, the stable water-stop performance is high when the number of MDI-based isocyanates is about 48 parts or more. It can be seen that when the number of added MDI-based isocyanates is low, the water stopping performance is as low as about 20 mm. Thus, it can be seen that the water stoppage is greatly dependent on the number of MDI-based isocyanate parts.

Example 2 Glycerin was subjected to addition polymerization of 25 mol% of propylene oxide (PO) or ethylene oxide (EO) with a molecular weight of 5
The weight ratio of ethylene oxide (EO) was changed to 0, 5, 10,
Each polyol 1 adjusted to 15, 20, 25 mol% ratio
In 00 parts, 5 parts of ethylene glycol (EG) of a low molecular weight diol as a cross-linking agent, 1.5 parts of water as a foaming agent, 0.2 parts of Dabco33LV 0.2 (amine-based catalyst) as a catalyst and stannas octate (organic tin compound catalyst) ) 0.2-
0.4 parts, a foam stabilizer having a siloxane content of 20%, a molecular weight of about 8,000 and a polyether terminal being an —OH group (Silicone A) is used. Liquid MDI modified with carbodiimide as an isocyanate (NCO = about 29%) ) Was used to create the form. Table 2 shows the physical properties and waterproofness of the obtained foam.

[0023]

[Table 2]

From the results shown in Table 2, the water stoppage is determined by the E of the polyol.
50 to 6 when the O content (%) is in the range of 0 to 20%
A high water pressure of about 0 mm is maintained. However, when the EO content exceeds about 20%, the water stoppage decreases.

Example 3 Glycerin was subjected to addition polymerization of propylene oxide (PO) or ethylene oxide (EO) with a molecular weight of 3000 (O
H equivalent = 1000), 5000 (OH equivalent = 166)
6) at 6800 (OH equivalent = 2666), Eo mol%
Foams were made according to the formulation in Table 3 using about 12 to 15 polyols. Table 3 shows the physical properties and waterproofness of the obtained foam.

[0026]

[Table 3]

As can be seen from the results, even if the molecular weight of the polyol is changed, a high level of water stopping performance is maintained if the MDI-based isocyanate is at least 42 parts. Further, those having a low molecular weight of the polyol generally have a disadvantage in terms of the brittleness of the foam (elongation / strength is reduced). However, when the molecular weight of the polyol is 4000 (OH equivalent = 1333) or more, the tensile strength, Elongation is improved. Thus, it can be seen that the brittleness of the foam is improved by setting the hydroxyl equivalent to 1300 or more.

Example 4 As a method for improving the water stoppage, there is a waterproofing additive. After PO addition to the glycerin used in Example 1, EO was added, and 100 parts of a polyether polyol having a molecular weight of 5000 EO and a molar content of about 15% and 5 parts of ethylene glycol (EG) of a low molecular weight diol as a crosslinking agent, 1.5 parts of water,
Dabco 33LV (amine based catalyst) and stannas octate (organic tin compound catalyst) as catalysts, reactive silicone A having terminal OH group as foam stabilizer, liquid MDI modified with carbodiimide as isocyanate (NCO = about 29
%). As a waterproofing additive, (A) solid petroleum resin FTR-6100 (manufactured by Mitsui Chemicals, Inc.) and (B) petroleum liquid liquid paraffin (manufactured by Kanada Yuka Co., Ltd.) are used in a one-to-one correspondence.
(C) petroleum liquid paraffin (manufactured by Kanada Yuka Co., Ltd.), (D) petroleum liquid polybutene LV
-100 (manufactured by Nippon Petrochemical Co., Ltd.), and (E) a solid petroleum resin obtained by polymerizing a C9 fraction (melting point: 100 ° C.) to prepare a foam. Table 4 shows the physical properties and waterproofness of the obtained foam.

[0029]

[Table 4]

In the present invention, it is possible to provide a waterproofness of 60 mm without adding a waterproofing additive. However, when a solid waterproofing additive is added at room temperature, the waterproofing performance can be further improved. Is further improved. However, it is not preferable to use a liquid that is liquid at normal temperature because the water stopping performance is rather deteriorated.

Example 5 Glycerin was added with propylene oxide (PO) or ethylene oxide (EO) to effect addition polymerization of 100 parts of a polyol having a molecular weight of 5000, a low molecular weight diol ethylene glycol (EG) as a crosslinking agent, and the number of water parts as a foaming agent were changed. Thus, the MDI-based isocyanate was changed.
0.2 parts of Dabco33LV (an amine catalyst manufactured by Sankyo Air Products Co., Ltd.) and 0.2 to 0.4 parts of stannas octate (organic tin compound catalyst) as catalysts, and a foam stabilizer is a polydimethylsiloxane-polyalkylene ether graft copolymer. A polymer (Silicone A) having a siloxane content of about 20% and a molecular weight of about 8,000 and having a polyether terminal of --OH group (Silicone A) is used. Liquid MDI (NCO = about 29%) modified with carbodiimide as an isocyanate and crude MDI (NCO% = about 29%) blended at a weight ratio of 3: 1 was used. Table 5 shows the physical properties and waterproofness of the obtained foam.

[0032]

[Table 5]

From these results, it is found that the water stopping performance does not increase even if the isocyanate amount is increased to 42 parts or more by increasing the number of water parts. This is thought to be because the reaction between water and the isocyanate of the blowing agent is prioritized and the resinification reaction is delayed and the stable region is narrow. To improve this, the addition of a crosslinking agent is essential. The use of a crosslinking agent in this formulation increases the internal self-heating value and promotes the reaction. Further, the rapid reactivity has an effect of helping the cell to be miniaturized and preventing cracking of the foam. In order to produce a foam in this way, a foam having high water-stopping performance can be prepared by considering the MDI isocyanate to be 42 parts or more depending on the number of water parts of the foaming agent and the number of crosslinking agents used together.

In order to compare the reactivity between the MDI-based isocyanate and TDI (tolylene diisocyanate), the demolding speed of molding was examined by combining EO-containing highly reactive PPG. In the formulation shown in the table below, the mold temperature was 60 ° C, and the temperature was gradually increased to 100 ° C after the injection of the raw materials. The thickness of the product was changed and the demolding time was measured.

[0035]

[Table 6]

The demolding time was about 5 to 6 minutes even when the product thickness was changed from that of the highly reactive raw material system. In the conventional formulation using TDI isocyanate, the demolding time requires twice or more the time required for MDI isocyanate regardless of the thickness. That is, it can be said that the high-reaction raw material system of the present invention has a water stopping function and is excellent in productivity. Comparative Example 1 A dimer acid ester (OHV) obtained from diethylene glycol and dimer acid as a special polyol of the prior art
= 80) and the demolding time for the formulation using
Shown in

[0037]

[Table 7]

[0038] Formulations using special polyols exhibit high water stopping performance, but have the disadvantage of low reactivity and poor productivity. However, according to the present invention, the reaction time is two to three times faster while exhibiting the same water stopping performance, and the productivity is remarkably improved.

Example 6 A foamed slab and a foamed mold were produced based on the formulation of Example 1. In the molded foam, a self-skin layer was formed, and the water stopping performance exerted by the self-skin layer was observed. Table 8 shows the physical properties and waterproofness of the obtained foam.

[0040]

[Table 8]

By having a self-skin layer on at least one side, the water stopping performance is improved by a factor of two. It is considered that the difference in adhesion between the self-skin layer and the cell layer on the water-stop surface improved the interfacial water-stop performance. Thus, it was found that the combination of the improvement of the water stoppage by the formulation and the self-skin layer further improved the water stoppage.

[0042]

As described above, according to the present invention, even when a PPG-based polyol is used, it is possible to provide a high water-stopping foam sealing material having almost the same numerical values as those obtained when a special polyol is used. PPG-based polyols that can be used are commercially available in a wide range of molecular structures and can be easily obtained. By using these, the physical properties such as the hardness of the foam material can be freely adjusted. The raw material price is also low, so that a low-cost foam sealing material can be provided. The curing rate can be increased by combining the MDI isocyanate and the EO-containing highly reactive PPG-based polyol. In general, a polyurethane product having a large thickness has a large volume, and therefore has a high self-heating value, so that the production speed is easily increased. However, a product having a small product thickness has a smaller self-heating value than this, resulting in a decrease in productivity. In the present invention, since a highly reactive raw material can be used, a product having a high productivity can be obtained regardless of the product thickness. In addition, since the reaction speed of the product is high, the initial strength of the product, that is, the strength that can be handled is quickly obtained. For this reason, it is possible to immediately start the secondary processing steps, for example, operations such as double-sided tape lamination, punching, and product cutting. This is an epoch-making production system that is effective in reducing inventory and inventory space. Since diphenylmethane diisocyanate (MDI) is used as the isocyanate component, the working environment is improved as compared with tolylene diisocyanate (TDI). Tolylene diisocyanate is a specialized material and a difficult-to-handle raw material that requires special attention to raw material management and the environment, but MDI is relatively easy. Since a polyether raw material is used as the polyol raw material, it is excellent in hydrolyzability unlike the ester-based raw material, and can have stable water stopping performance for a long time.

[Brief description of the drawings]

FIG. 1 shows a U-shaped water stoppage test apparatus used in the present invention.

FIG. 2 is a diagram showing the relationship between the number of isocyanate parts used and water stoppage in Example 1.

[Explanation of symbols]

 1 sample 2 water pressure 3 acrylic plate

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08G 101: 00) C08G 101: 00) (72) Inventor Hideto Ogura 1170 Ako, Komagane-shi, Nagano F-term (reference) 4H017 AA03 AB03 AC04 AC13 AC16 AC19 AD06 AE03 4J034 BA03 DB04 DB05 DB07 DC50 DG03 DG04 DG08 DG10 HA01 HA07 HA11 HC03 HC12 HC71 JA01 KA01 KA04 KB04 KB05 KC18 KD04 KD07 KD12 KD07

Claims (4)

[Claims] 1. A highly water-resistant polyurethane foam sealing material comprising a flexible urethane foam obtained from a polyol, an isocyanate, a foam stabilizer, a crosslinking agent, and a foaming agent, wherein the polyol is a PPG-based polyol.
With respect to 00 parts by weight, an MDI-based isocyanate is used as an isocyanate in an amount of 42 parts by weight or more, a silicone having a group reactive with isocyanate or polyol as a foam stabilizer, and an active hydrogen which reacts with an isocyanate group as a crosslinking agent. High water-resistant polyurethane foam sealing material having characteristics of a density of 35 kg / m ³ or more, a water-stop retention time of 24 hours and a water-stop pressure of 50 mm or more, characterized by using water as a foaming agent. . 2. The highly water-resistant polyurethane foam sealing material according to claim 1, wherein the PPG-based polyol has an ethylene oxide (EO) addition molar ratio of 1% to 20% and a hydroxyl equivalent of 1300 or more. 3. The highly water-resistant polyurethane foam sealing material according to claim 1, wherein the crosslinking agent is a polyhydric alcohol having a functional group number in the range of 2 to 4 and a hydroxyl value of 600 mg KOH / g or more. 4. The highly waterproof polyurethane foam sealing material according to claim 1, wherein a self-skin layer is provided on at least one surface of the polyurethane foam.