JPH10101923A - Stress-relaxtive one-package moisture-curing composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stress-relaxative one-package moisture-curing composition excellent in stress relaxation, free from the risk of undergoing break or peel with time and useful as a sealing material for siding boards. SOLUTION: This composition is prepared by mixing a urethane prepolymer obtained by reacting a polyol component having a molar trifunctional polyol to difunctional polyol ratio of 1/7 to 1/25 with diphenylmethane-4,4-diisocyanate in such an amount as to give an NCO/OH of 1.4-1.8 with 0.01-0.3mol, per mol of the NCO groups of the urethane prepolymer, of an oxazolidine compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a moisture-curable urethane-based sealing material, which has the property of relieving stress when stress is applied, and has low surface tack.
The present invention relates to a one-pack type urethane sealing material for architectural use having excellent material properties.

[0002]

2. Description of the Related Art Conventionally, a modified silicone-based sealing material has been used for applications requiring a property of relaxing a stress when the stress is applied (hereinafter referred to as stress relaxation property). I have. On the other hand, moisture-curable polyurethane has been difficult to use because it is an elastic body and has a small stress relaxation property when used in applications requiring stress relaxation properties. That is, the conventional urethane-based sealing material is
Based on an active isocyanate group-containing urethane prepolymer synthesized by the reaction of a polyol component of a functional polyol and a bifunctional polyol with a polyisocyanate component, from a plasticizer, a filler such as calcium carbonate, other thixotropic agents, a catalyst, etc. Since it is made of a rubber-like elastic body and behaves as an elastic body against stress, it hardly relieves stress.
At the joints of the siding board frequently used for the outer wall of a detached house, etc., the siding board shrinks with the elapse of time due to evaporation of moisture, so that stress is applied in a direction in which the joints spread. If a sealing material having high restorability against displacement and hardly relieving stress is used in a portion where such joints are opened, stress is continuously applied to the bonding interface, and there is a high risk that the sealing material is broken or peeled. For this reason, there is a demand for a siding board sealing material that has a high stress relaxation property after deformation even when a stress is applied and does not leave stress at an adhesive interface.

[0003]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems, and has excellent stress relaxation properties, has no danger of breaking or peeling over time, and is useful as a sealing material for siding boards. It is an object of the present invention to provide a one-part moisture-curable composition.

[0004]

That is, the inventors of the present invention disturb the physical properties of a rubber elastic body, which is a characteristic of urethane, by setting the blend ratio of trifunctional / bifunctional polyol components within a certain range. The present inventors have found that the present invention can have a stress relaxation property without any problem.

That is, the present invention relates to a method in which a polyol having a molar ratio of trifunctional polyol / bifunctional polyol of 1/7 to 1/25 and diphenylmethane-4,4 diisocyanate are mixed with NCO / OH = 1.4-1. A urethane prepolymer obtained by reacting the oxazolidin compound in the range of 0.8 to 1.8, and containing from 0.01 to 0.3 mol of an oxazolidine compound per 1 mol of NCO groups of the urethane prepolymer. A one-part moisture-curable composition is provided.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The one-component moisture curable composition capable of relaxing the stress of the present invention contains a bifunctional polyol and a trifunctional polyol in a certain range of mixing ratio (molar ratio). The bifunctional polyol is a general term for alcohols in which two hydrogens have been substituted with hydroxyl groups. For example, one or more alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide, and tetrahydrofuran are represented by two It is a product obtained by addition polymerization of a compound having active hydrogen. Examples of the compound having two active hydrogens include dihydric alcohols, primary amines, and dihydric phenols. Dihydric alcohols include ethylene glycol,
Propylene glycol, butanediol, diethylene glycol, primary amines include methylamine, t
Examples of ert-butylamine and dihydric phenols include resorcinol and bisphenols.
Specifically, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyoxypropylene glycol, polytetramethylene ether glycol, polyoxybutylene ether glycol,
Polyolefin diols such as polybutadiene and polyisoprene, and polyester diols such as adipate diols, lactone diols, and castor oil are preferable. As the bifunctional polyol, one or more of these bifunctional polyols may be used in combination.

[0007] The trifunctional polyol is a general term for alcohols in which three hydrogens have been substituted with hydroxyl groups. For example, one of alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide and tetrahydrofuran can be used.
It is a product obtained by addition polymerization of one or more species to a compound having three active hydrogens. Examples of the compound having three active hydrogens include trihydric alcohols, alkanolamines, and trihydric phenols. As trihydric alcohols, glycerin, hexanetriol, trimethylolpropane, etc., as alkanolamines, triethanolamine, tripropanolamine, etc., and as trihydric phenols,
Pyrogallol, pyrologlucinol and the like can be mentioned. Specifically, polyolefin-based triols such as polyhexanetriol, polybutadiene, and polyisoprene, and polyester-based triols such as adipate-based triol, lactone-based triol, and castor oil are preferred. As the trifunctional polyol, one or more of these trifunctional polyols may be used in combination.

[0008] These bifunctional polyols and trifunctional polyols preferably have a weight average molecular weight of about 100 to 10,000, more preferably about 1,000 to 7000.

The compounding molar ratio of the polyol component used in the present invention is higher than the compounding ratio of the bifunctional polyol used in the conventional urethane prepolymer, and the ratio of the crosslinking points provided by the trifunctional polyol is reduced. Gives ease. That is, the mixing molar ratio of the trifunctional and bifunctional polyols is trifunctional polyol / bifunctional polyol = 1/7 to 1/25, preferably 1/15 to
1/20 is good. If it is more than 1/7, the stress is not relaxed as in the case of conventional polyurethane which is an elastic body, and if it is less than 1/25, the ratio of the bifunctional polyol which does not give a cross-linking point becomes too large to harden.

The isocyanate component used in the present invention is diphenylmethane-4,4 diisocyanate (hereinafter referred to as MD).
I). The mixing ratio of the polyol component and MDI is NCO / OH (index) = 1.4 to 1.8,
Preferably it is 1.45 to 1.60. If the index is less than 1.4, the viscosity increases and the workability of the sealant deteriorates. If it exceeds 1.8, foaming occurs. When the index is kept low at 1.8 or less, the adhesiveness of the obtained urethane prepolymer is reduced. Therefore, MDI having high activity is used as the isocyanate component of the present invention.
When the isocyanate component used is toluene diisocyanate (hereinafter referred to as TDI) or aliphatic isocyanate,
Curability and adhesiveness decrease.

In order to produce a urethane prepolymer from the polyol component and the isocyanate component of the present invention, ordinary production conditions for the urethane prepolymer may be used. That is, the polyol component and the isocyanate component are reacted at a reaction temperature of 5
The reaction may be performed at about 0 to 100 ° C. under normal pressure.

An oxazolidine compound is added to the urethane prepolymer of the present invention obtained as described above. The oxazolidine compound is a compound having a saturated 5-membered heterocyclic ring containing oxygen and nitrogen, and having an oxazolidine ring which opens in the presence of moisture (water) and reacts with an isocyanate group to cure. The oxazolidine compound used is
The mixing ratio is 0.01 to 0.3 mol, particularly 0.1 to 0.2 mol, per 1 mol of the NCO group of the urethane prepolymer. As described above, the urethane prepolymer of the present invention has a low index (NCO / OH ratio) and thus has low curing reactivity. However, the addition of an oxazolidine compound prevents the low curing reactivity. Can be. Furthermore, since the ratio of the bifunctional polyol of the polyol component used in the present invention is large, the cross-linking structure is not strong as a whole, and the cross-linking becomes loose and the tensile strength of the obtained urethane prepolymer is not sufficient, but by adding the oxazolidine compound, A decrease in tensile strength can be suppressed. That is, by adding the oxazolidine compound, the crosslinking can be loosened, and the curing reactivity can be maintained without deteriorating while providing stress relaxation. The compounding ratio of the oxazolidine compound is 0.
If the amount is less than 01 mol, the curability and physical properties are not sufficient.
If it exceeds 3, the stress relaxation property is undesirably reduced.

Specific examples of the oxazolidine compound of the present invention include N-hydroxyalkyloxazolidine and its polyisocyanate adducts, oxazolidinesilyl ether, carbonate oxazolidine, ester oxazolidine and the like.

The N-hydroxyalkyloxazolidine is carried out, for example, by a dehydration condensation reaction between an alkanolamine and a ketone or aldehyde. Specific examples of N-hydroxyalkyloxazolidine include 2-isopropyl-3- (2-hydroxyethyl) oxazolidine (hereinafter, referred to as hydroxyalkyloxazolidine (1)), 2- (1-methylbutyl) -3- (2- Hydroxyethyl) oxazolidine (hereinafter referred to as hydroxyalkyloxazolidine (2)), 2-phenyl-3-
(2-hydroxyethyl) oxazolidine (hereinafter referred to as hydroxyalkyloxazolidine (3)), 2-
(P-methoxyphenyl) -3- (2-hydroxyethyl) oxazolidine (hereinafter referred to as hydroxyalkyloxazolidine (4)), 2- (2-methylbutyl)-
3- (2-hydroxyethyl) -5-methyloxazolidine (hereinafter referred to as hydroxyalkyloxazolidine (5)
).

[0015]

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The oxazolidine silyl ether is obtained by mixing the above-mentioned N-hydroxyalkyloxazolidine with trimethoxysilane, tetramethoxysilane, triethoxysilane, dimethoxydimethylsilane, vinyltrimethoxysilane, vinyltriethoxysilane, and γ-glycidoxypropyltriyl. It is obtained by a reaction with an alkoxysilane such as methoxysilane and γ-glycidoxypropyltriethoxysilane.

Specifically, the following oxazolidine silyl ethers (1) to (3) are mentioned.

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The carbonate oxazolidine is, for example,
And carbonate oxazolidine obtained by the method of JP-A-5-117252. Specifically, for example, by reacting a hydroxyalkyl oxazolidine such as the above-mentioned hydroxyalkyl oxazolidine (1) with a carbonate such as diallyl carbonate, dimethyl carbonate or dipropylene carbonate using a polyhydric alcohol such as diethylene glycol or glycerin. Obtainable.

Such a carbonate oxazolidine is represented by the following formula (a).

Embedded image (In the formula, n is an integer of 1 to 10, R ^a and R ^b are each independently an organic group having 1 to 8 carbon atoms. R ^c and R ^c
d is each independently a hydrogen atom or an organic group having 1 to 8 carbon atoms. And the like, and more specifically, the following carbonate oxazolidine (1).

[0020]

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Ester oxazolidine is described, for example, in US Pat. No. 3,661,923 and US Pat.
Various ester oxazolidines such as ester oxazolidine obtained by the method of JP-A No. 545 can be used, and for example, can be obtained by reacting the above-mentioned hydroxyalkyl oxazolidine (1) with a lower alkyl ether of dicarboxylic acid or polycarboxylic acid. . Specific examples include the following ester oxazolidine (1). Further, a commercially available product such as a hardener OZ manufactured by Bayer and represented by the following ester oxazolidine (2) can also be used.

[0022]

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The oxazolidine compound of the present invention includes:
An oxazolidine compound having three or more oxazolidine rings in one molecule may be used, and this compound is reacted with an N-hydroxyalkyl oxazolidine represented by the following formula and a polyisocyanate compound to obtain a compound having three or more oxazolidine rings. It is synthesized as a compound having two or more oxazolidine rings.

[0024]

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Here, R ¹ is a linear or branched divalent aliphatic hydrocarbon group having 2 to 3 carbon atoms, for example, an alkylene group, alkenylene group or alkynylene group. R ² and R ³ each independently represent a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. N-hydroxyalkyl oxazolidine represented by the above formula,
It is synthesized from the corresponding aldehyde or ketone and N-hydroxyalkylamine by a known method.

As the aldehyde, formaldehyde,
Acetaldehyde, propionaldehyde, butyraldehyde, isobutyraldehyde, valeraldehyde, 2
Aliphatic aldehydes such as -methylbutyraldehyde, 3-methylbutyraldehyde, hexylaldehyde, 2-methylpentylaldehyde, octylaldehyde, 3,5,5-trimethylhexylaldehyde; benzaldehyde, methylbenzaldehyde, trimethylbenzaldehyde, ethylbenzaldehyde, isopropyl Aromatic aldehydes such as benzaldehyde, isobutylbenzaldehyde, methoxybenzaldehyde, dimethoxybenzaldehyde, and trimethoxybenzaldehyde; acetone, methylethylketone, methylpropylketone, methylisopropylketone, diethylketone, methylbutylketone, methylisobutylketone, methyl-t-butylketone, diisobutyl Ketone, cyclopentanone, cyclohexanone Ketone is preferred.

The N-hydroxyalkylamine includes
Bis-N- (2-hydroxyethyl) amine, bis-N
-(2-hydroxypropyl) amine and N- (2-
(Hydroxyethyl) -N- (2-hydroxypropyl)
Amines are preferred.

The polyisocyanate compound is a polyisocyanate having an organic group, for example, a polyhydric alcohol such as glycerin, hexanetriol, trimethylolpropane or polypropylene glycol, paraphenylene diisocyanate, tolylene diisocyanate, tetramethylene. Reaction products of diisocyanate, hexamethylene diisocyanate, xylene diisocyanate, octadecyl diisocyanate, naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate, isophorone diisocyanate and modified products thereof, or tetramethylene diisocyanate, hexamethylene diisocyanate (HDI) The isocyanurate is obtained by trimerizing the diisocyanate compound in the presence of a catalyst. Include compounds having 3 or more isocyanate groups in one molecule obtained by forming the door ring, these polyisocyanate compounds may be a single 2
More than one species may be used in combination.

Specific examples of such a compound having three or more oxazolidine rings in one molecule include a polyfunctional oxazolidine compound (1) represented by the following formula and a polyfunctional oxazolidine compound (2) represented by the following formula: ) And the like.

[0030]

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The above-mentioned various oxazolidine compounds are described in detail in Japanese Patent Application No. 7-331373.
The present invention can use these.

The composition of the present invention contains, in addition to the above compounds,
If necessary, filler, plasticizer, pigment, antistatic agent, flame retardant, thixotropic agent, silane coupling agent,
A dispersant, an antioxidant, a solvent and the like may be blended.

Examples of the filler include calcium carbonate, carbon black, clay, talc, titanium oxide, quicklime, kaolin, zeolite, diatomaceous earth, vinyl chloride paste resin, glass balloon, vinylidene chloride resin balloon and the like. Alternatively, they can be used in combination.

The composition of the present invention may use a solvent, and preferably uses an aromatic hydrocarbon solvent. As the aromatic solvent, xylene, toluene and the like are preferable.

Examples of the plasticizer include dioctyl phthalate (DOP), dibutyl phthalate (DBP), dilauryl phthalate (DLP), dibutyl benzyl phthalate (BBP), dioctyl adipate, diisodecyl adipate, trioctyl phosphate, and tris (chloroethyl). ) Phosphate, tris (dichloropropyl) phosphate, propylene glycol adipate polyester, butylene glycol adipate polyester, alkyl epoxystearate, epoxidized soybean oil, etc., and can be used alone or in combination. . Examples of the pigment include organic pigments such as an azo pigment and a copper phthalocyanine pigment, and various inorganic pigments. Examples of the thixotropic agent include Aerosil (manufactured by Nippon Aerosil Co., Ltd.) and Dispalon (manufactured by Kusumoto Kasei Co., Ltd.).

In general, examples of the antistatic agent include ionic compounds such as quaternary ammonium salts and amines, and hydrophilic compounds such as polyethylene glycol and ethylene oxide derivatives. Examples of the adhesion-imparting agent include a terpene resin, a phenol resin, a terpene-phenol resin, a rosin resin, and a xylene resin.
Examples of the flame retardant include chloroalkyl phosphate, dimethylmethylphosphonate, bromine, phosphorus compounds, ammonium polyphosphate, diethylbishydroxyethylaminophosphate, and the like.

The method for producing the one-part urethane adhesive composition of the present invention is not particularly limited.
It is preferable to add other additives as necessary, knead the mixture sufficiently under reduced pressure or an inert atmosphere, and uniformly disperse the composition.

[0038]

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to the following examples.

[Synthesis of hydroxyalkyl oxazolidine] Diethanolamine 100.
1 g and 100 ml of benzene were added. 2 in the resulting solution
100.2 g of -methylpentanal was added dropwise. After completion of the dropwise addition, the flask was immersed in an oil bath, and the reaction mixture was reacted under reflux conditions for 8 hours. Further, benzene was distilled off from the reaction mixture to obtain 187 g of N-hydroxyethyl-2- (1-methylbutyl) -1,3-oxazolidine, which was the above-mentioned hydroxyalkyl oxazolidine (2). It is shown as oxazolidine compound A in Table 1 below.
100 g of this 2- (1-methylbutyl) -3-oxazolidine ethanol and xylylene diisocyanate
5 g were mixed at room temperature and reacted at 50 ° C. for 1 hour and further at 80 ° C. for 8 hours. Yield 151 g. It is shown as oxazolidine compound B in Table 1 below.

(Examples 1 to 6) [Production example of urethane prepolymer] 250 g of polyoxypropylene ether triol EXCENOL5030 (produced by Asahi Glass Co., Ltd.) having three hydroxyl groups and having an average molecular weight of 5000, and two 1500 g of hydroxyl groups Having an average molecular weight of 2000, EXCENOL 2020 (manufactured by Asahi Glass Co., Ltd.), and 832
g of dioctyl phthalate (manufactured by Mitsubishi Chemical Corporation) was placed in a reaction vessel and dehydrated under reduced pressure at 110 ° C. and 50 mmHg for 2 hours. Thereafter, the reaction product is cooled to 80 ° C.
When ex = 1.6, 330 g of diphenylmethane-4,4′-diisocyanate (MDI, manufactured by Mitsubishi Chemical Corporation) was added and stirred. The reaction was carried out at 80 ° C. for 30 hours to obtain an MDI prepolymer such that the free isocyanate was 1.43% or less. 18.5 g of N-hydroxyethyl-2- (1-methylbutyl) -1,3-oxazolidine was added to obtain a urethane prepolymer composition.

140 parts by weight of this urethane prepolymer is placed in a kneading vessel filled with dry nitrogen gas, and further, 120 parts by weight of calcium carbonate (Sealets 200) manufactured by Maruo Calcium Co., Ltd. as a filler, and a silane coupling agent A-187 manufactured by Nippon Unicar Co., Ltd.
17 parts by weight of xylene (manufactured by Kanto Chemical Co., Ltd.) as a solvent were added and sufficiently kneaded in a vacuum stirrer to obtain a one-part moisture-curable composition of the present invention.

(Comparative Examples 1 to 3) Compositions were obtained in the same manner as in the Examples except that the components of the composition were formulated as shown in Table 1 below.

[Evaluation of Physical Properties of Composition] Tack Free Time (TFT) Each of the obtained compositions was formed into a sheet having a length of 100 mm × a width of 100 mm × a thickness of 5 mm, and the tack free time was measured. The tack-free time is indicated by the time (minutes) taken until the molded product does not adhere to the finger even when the molded product is pressed with a finger. H-type 50% tensile modulus 50% tensile modulus was measured using JIS A5758 as the H-type. The unit is [kg / cm ² ]. H-Type Tensile Strength Using JIS A5758 as the H-type, the maximum stress up to the time of cutting under tension was measured, and the value was shown as a value per original cross-sectional area of the test piece. The unit is [kg / cm ² ]. H-type elongation Using JIS A5758 as the H-type, the elongation in the tensile direction caused by applying a tension was measured, and the result was shown as a ratio of the elongated length to the original length. The unit is [%]. Stress relaxation property A test piece prepared according to JIS A5758 was stretched from a thickness of 12 mm to 15.6 mm, and kept at 60 ° C. for 3 days.
It was left at 20 ° C. for 8 hours except for the load, and the ratio of the increased thickness elongation deformation to the thickness before deformation was shown. Units〔%〕
It is. Table 1 shows the results.

[0044]

[Table 1]

[0045]

EFFECTS OF THE INVENTION The one-part moisture-curable composition of the present invention capable of relaxing a stress does not impair the physical properties of a conventional urethane prepolymer in terms of tack-free time, 50% modulus and strength, and has a stress relaxing property. Since it is high, it can be applied particularly as a sealing material for a portion such as a siding board that shrinks over time and opens joints.

Claims (1)

[Claims] 1. A method in which a polyol having a molar ratio of trifunctional polyol / bifunctional polyol of 1/7 to 1/25 and diphenylmethane-4,4 diisocyanate are mixed with NCO / OH
= Urethane prepolymer obtained by reacting in the range of 1.4 to 1.8, and NC of the urethane prepolymer
Oxazolidine compound 0.01 to 1 mol of O group
A one-pack moisture-curable composition capable of relaxing stress, containing 0.3 mol.