JPH055088A - Reactive hot-melt elastic sealant composition - Google Patents

Abstract

PURPOSE:To provide the subject one-pack type moisture-curable sealant composition comprising a high mol.wt. polyurethane prepolymer and a thermoplastic urethane multi-block copolymer resin, holding. good initial adhesive strength and successive adhesive power, and having good durability and cold resistance. CONSTITUTION:The objective composition comprises (A) a polyurethane prepolymer preferably in an amount of 20-60wt.% and (B) a thermoplastic urethane multi-block copolymer resin, preferably in an amount of 5-30wt.%, the polyurethane prepolymer A being prepared by reacting (i) a polyether polyol having a mol.wt. of 6000-400000 and containing hydroxyl groups at the molecular ends with (ii) an excessive amount of a polyisocyanate compound, preferably in an equivalent ratio of 1:1.5-3.5.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a reactive hot melt elastic sealant composition, and more particularly to a composition having an initial adhesive strength and an adhesive strength over time and having excellent durability, particularly cold resistance (for example, -30 to-). The present invention relates to a one-component, moisture-curing type reactive hot melt elastic sealant composition having rubber elasticity at 40 ° C.

[0002]

2. Description of the Related Art In recent years, in the automobile industry, adhesion around windows and adhesion of various parts are rapidly progressing, and the adherend is also formed by conventional glass or coating. Some steel sheets are changing to plastic resin. Particularly, in an adhesive sealant for automobiles, excellent adhesive strength and durability (maintaining desired adhesive force even under high temperature or cold (eg, -30 to -40 ° C)) are required, and Sufficient initial adhesion is required without the need for temporary fixing. In addition, the adhesive sealing material for automobiles is required to have excellent rubber elasticity so as to absorb vibration during driving.

However, although the conventional hot melt sealing material is excellent in initial adhesion and workability, it has drawbacks in durability at high temperature and cold resistance, especially under cold conditions (for example, -30 to -40). At ℃), it becomes plastic-like and loses rubber elasticity. Further, the reactive sealing material has good durability at high temperature, but has poor initial adhesive strength, and it takes time to achieve desired initial adhesion without temporary fixing. Therefore, the development of a sealing material having both the characteristics of these hot melt sealing material and reactive sealing material is underway, but it is difficult to adjust the initial holding strength and the elasticity of the sealing material, especially in cold weather (- At present, it is extremely difficult to have rubber elasticity in the physical properties at 30 to -40 ° C.

[0004]

Means for Solving the Problems The inventors of the present invention have made earnest studies to provide a reactive hot melt elastic sealing material having the above holding strength and cold rubber elasticity.
The polyurethane prepolymer obtained by the reaction of a high molecular weight polyether polyol and an excess amount of a polyisocyanate compound, in combination with a specific thermoplastic resin compatible with it, exhibits the characteristics of hot melt and is durable. It was found that rubber elasticity having excellent performance, particularly cold resistance at −30 to −40 ° C., can be exhibited, and the present invention has been completed.

That is, the present invention has a molecular weight of 6000-4.
Polyurethane prepolymer obtained by reacting an excess amount of polyisocyanate compound with polyether polyol having a hydroxyl group at the end of 0000 (hereinafter referred to as ultra-high molecular weight polyether polyol), and thermoplastic urethane multi-block copolymer The present invention provides a reactive hot melt elastic sealing material composition containing a resin.

The ultra high molecular weight polyether polyol in the present invention has the formula:

[Chemical 1] [Wherein R is a hydrocarbon residue having 2 to 6 carbon atoms, especially an alkylene group and α is an integer of 2 to 8, preferably 2 to 4], for example, in the case of α = 2 Ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, 1,6-hexanediol; glycerin, trimethylolpropane, triethylenetriol, 1,2,6-hexanetriol when α = 3; pentaerythritol when α = 4; α =
6 is sorbitol; α = 8 is sucrose], and is obtained by ring-opening polymerization of propylene oxide or propylene oxide / ethylene oxide in the presence of one or more of [Shoose] and a suitable catalyst (eg, metal catalyst). ,formula:

[Chemical 2] Or

[Chemical 3] [In the formula, n is an integer of 13 to 350, m is an integer of 0 to 440, R and α have the same meanings as described above] (for example, polyoxypropylene diol, polyoxypropylene ethylene diol, (Polyoxypropylene triol, polyoxypropylene ethylene triol, polyoxypropylene tetraol, polyoxypropylene ethylene tetraol, etc.), of which the molecular weight is 6000-4000.
0, preferably 10,000 to 300 in terms of the physical properties of the sealant and the properties and workability of the polyurethane prepolymer
The one of 00 is used. There is no problem even if a ring-opening polymerization of butylene oxide is used in place of the propylene oxide (PO) or ethylene oxide (EO). When the molecular weight is less than 6000, it will be cold.
The elongation of (-30 to -40 ° C) is insufficient, and the hardness becomes too high, and even if it exceeds 40000, there is no problem in physical properties,
At present, there are too many by-products and it is difficult to synthesize. In addition, in these ultra high molecular weight polyether polyols, the number of functional groups (OH number, that is, α) is 2
-4, especially 2-3 are preferable.

Since such ultra-high molecular weight polyether polyol generally has an extremely low Tg of -70 to -60 ° C, it contributes to the development of elastomer physical properties in cold weather as its isocyanate cured product. Polyols having a relatively low Tg include polybutadiene polyols and hydrogenated polybutadiene polyols, but these have poor compatibility with thermoplastic urethane multi-block copolymer resins and are not practical.

Examples of the polyisocyanate compound in the present invention include 2,4- or 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate (MDI), 1,3- or 1,4-xylylene diisocyanate, It is possible to use 1,5-naphthalene diisocyanate, isoferon diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, and trimethylolpropane adduct of these polyisocyanates, which are used for ordinary urethane resins, but the moisture curing rate , MDI is particularly preferable in terms of safety and industrial price.

The polyurethane prepolymer used in the present invention comprises the above-mentioned ultra-high molecular weight polyether polyol and an excess amount of a polyisocyanate compound, usually at a temperature of 70 to 90 ° C.
It can be obtained by reacting for 0.5 to 5 hours. The ratio of these reaction components may be usually set so that the equivalent ratio of NCO / OH is within the range of 1.5 to 3.5, preferably 2-3. If this ratio is less than 1.5, the resulting polyurethane prepolymer will have a large amount of oligomers on top of the ultra-high molecular weight, causing a rapid increase in viscosity,
And the thermal stability when kept at 70-80 ° C becomes extremely poor,
On the other hand, when it exceeds 3.5, an excessive NCO group remains, and the above-mentioned heat retention stability at 70 to 80 ° C. becomes good, but the problem of foaming due to CO ₂ during moisture curing tends to become significant.

The thermoplastic urethane multi-block copolymer resin used in the present invention is basically a polyfunctional ring-containing active hydrogen-containing compound (molecular weight is usually 400 to 200).
0) and diol or triol components (eg ethylene glycol, 1,4-butanediol, 1,6-
Hexanediol, 1,8-octanediol, polycarbonate diol, polytetramethylene glycol,
Hydrogenated polybutadiene diol, polyacryl diol,
Polyoxyalkylene ether diol, polyoxyalkylene-added bisphenol, diols such as other compounds containing active hydrogen, trimethylolpropane, glycerin, triethylene triol, triols such as polyoxyalkylene ether triol) and excess polyisocyanate compound ( Although the above-mentioned examples can be used, those obtained by reaction with MDI are preferable from the viewpoint of safety and industrial cost because they increase the cohesive energy of urethane. As the polyfunctional ring-containing active hydrogen-containing compound, bisphenol resin, terpene resin,
It includes coumarone resin, xylene resin, rosin ester resin, styrene resin, phenol resin, terpene phenol resin, rosin resin, and polyester resin. The thermoplastic urethane-based multi-block copolymer resin (melting point is usually 70 to 100 ° C.) manufactured in this manner is commercially available, for example, from Toyo Kagaku Kenkyusho under the trade name of “thermoplastic resin Toyoace UB”. Has been done.

The thermoplastic urethane multi-block copolymer resin contributes to the improvement of the initial adhesive strength of the sealing material, but the urethane bond and the ring compound are introduced into the molecule by the above reaction. It can give a molar cohesive energy and become thermoplastic, and also has good compatibility with the polyurethane prepolymer due to the polarity of the ring compound and the urethane bond.

The reactive hot melt elastic sealant composition according to the present invention is characterized by containing the above-mentioned polyurethane prepolymer and thermoplastic urethane-based multi-block copolymer resin. It may be appropriately selected. Preferred basic compositions of the present invention include, for example, polyurethane prepolymers 20-60.
% (Weight%, the same below) (preferably 30 to 50%), thermoplastic urethane multi-block copolymer resin 5 to 30%
(Preferably 10 to 20%), filler 50% or less (preferably 20 to 40%), plasticizer 20% or less and additive 10% or less as required.

When the content of the polyurethane prepolymer is less than 20%, the basic physical properties do not extend in cold and the hardness is too high, and when it exceeds 60%, problems in workability tend to occur. Tends to become.

If the content of the thermoplastic urethane multi-block copolymer resin is less than 5%, the initial strength cannot be expected, and if it exceeds 30%, the physical properties at the time of cold tends to be unsatisfactory. ..

Examples of the filler include silicic acid derivatives, talc, metal powder, calcium carbonate, clay, carbon black and the like. If the content exceeds 50%, the viscosity as a sealing material is too high, and the adhesiveness and physical properties tend to be impaired.

Examples of the plasticizer include dibutyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, diisooctyl phthalate, diisodecyl phthalate, dibenzyl phthalate, butyl benzyl phthalate, trioctyl phosphate, epoxy plasticizer, toluene-sulfoamide, chloroparaffin. , Adipic acid ester, castor oil and the like. If the content exceeds 20%, the adhesiveness and initial strength tend to be poor.

Examples of the additives include viscosity adjusting solvents, curing catalysts, thixotropic agents (Benton, silicic acid anhydride, silicic acid derivatives, urea derivatives, etc.), dyes and pigments, ultraviolet absorbers, tackifiers, flame retardants, Examples include silane compounds and dehydrating agents.
If the content of these exceeds 10%, the properties and physical properties of the sealing material tend to deteriorate.

The composition of the present invention can be prepared, for example, by the following procedure. First, the thermoplastic urethane multi-block copolymer resin is melted at 80 to 100 ° C.,
This is put into a nitrogen-replaceable kettle kept at 90 ° C.
Then, the polyurethane prepolymer is added under a nitrogen atmosphere, and after stirring, a filler and, if necessary, a plasticizer are added, and the mixture is degassed and stirred under vacuum. Then, for example, a viscosity adjusting solvent and a curing catalyst are added as additives, and the mixture is vacuum degassed and stirred to prepare the composition of the present invention. In use, it may be applied at a temperature of 80 ° C or lower, preferably 70 ° C or lower. A hot melt applicator can also be used for automatic application using a robot.

[0019]

EXAMPLES Next, the present invention will be described more specifically with reference to Examples and Comparative Examples. Example 1 (1) Synthesis of Polyurethane Prepolymer Polyoxypropylene ethylene triol having a molecular weight of 12,500 [X-8805, trifunctional, EO content 12%, OH value 13.8] manufactured by Asahi Glass Co., Ltd. 2000 g was replaced with nitrogen. It is put in a reaction tank and dried under reduced pressure (10 mmHg or less) under reduced pressure. After confirming that the water content was below 0.05%, add 4,4'-diphenylmethane diisocyanate (MDI) to it.
158 g was added (NCO / OH = 2.61) and the temperature was adjusted to 80
Adjust to ± 5 ° C and let react for 1 hour. Then, 1% xylene solution of dibutyltin dilaurate (DBTDL) 1
g, and reacted at the same temperature for 2 hours to give a free NCO amount of 1.48% and a viscosity of 24,000 cps / 80 ° C., 380000 c
A polyurethane prepolymer of ps / 20 ° C. is obtained. (2) Preparation of Sealing Material 400 g of the polyurethane prepolymer of (1) above is put into a nitrogen-stirred stirring vessel, and the temperature is set to 80 ± 10 ° C. Next, 100 g of a thermoplastic urethane multi-block copolymer resin [manufactured by Toyo Kagaku Kenkyusho Co., Ltd., thermoplastic resin Toyoace UB] melted at 90 ° C. for 3 hours was added, and stirred at the same temperature for 20 to 30 minutes. After dissolving, 50 g of dicyclohexyl phthalate was added, 350 g of preliminarily dried carbon black and 100 g of calcium carbonate were respectively added, and the mixture was vacuum-stirred at 10 mmHg for 30 minutes, and then 50 g of xylene for adjusting viscosity and a curing catalyst (D
A 1% xylene solution of BTDL (0.3 g) is added, and the mixture is vacuum defoamed and stirred for 30 minutes, and then taken out into a sealed aluminum cartridge. In addition, the sealing material prepared in this (2) is "A-
1 "and 200 g of thermoplastic resin Toyo Ace U-
A sealing material "A-2" prepared in the same manner as in (2) above except that B is used. Similarly, in the other examples, two kinds of sealing materials are prepared.

Example 2 (1) Synthesis of polyurethane prepolymer Polyoxypropylene triol having a molecular weight of 15,000
[Asahi Glass Co., Ltd., X-8702, trifunctional, PO only, O
H value 11] 2000 g and molecular weight 10000 polyoxypropylene ethylenetriol [Asahi Glass Co., Ltd., X
-8202D, bifunctional, EO content 8%, OH value 11] 10
00g was put into a reaction tank whose nitrogen was replaced, and under vacuum (10m
Dry under reduced pressure at mHg or less). After confirming that the water content was below 0.05%, add 200 g of MDI to this (NCO
/OH=2.65), adjust the temperature to 80 ± 5 ° C., and react for 1 hour. Then, 1% xylene solution of DBTDL 1
g, and reacted at the same temperature for 2 hours, the amount of free NCO was 1.28%, the viscosity was 38,000 cps / 80 ° C., 460000 c
A polyurethane prepolymer of ps / 20 ° C. is obtained. (2) Preparation of sealing material Except for using the polyurethane prepolymer of (1) above,
According to the same formulation components and procedure as in Example 1 / (2),
Two kinds of sealing materials "B-1" and "B-2" are prepared.

Example 3 (1) Synthesis of polyurethane prepolymer Polyoxypropylene triol having a molecular weight of 30,000
[Asahi Glass Co., Ltd., X-8705, trifunctional, PO only, O
2000 g of H value of 6.1] is put into a nitrogen-replaced reaction tank and dried under reduced pressure (10 mmHg or less) under reduced pressure. Water content is 0.
After confirming that it became less than 05%, add 70g of MDI to it.
Was added (NCO / OH = 2.75), the temperature was adjusted to 80 ± 5 ° C., and the reaction was carried out for 1 hour. After that, 1% of DBTDL
Add 1 g of xylene solution, react at the same temperature for 2 hours,
Free NCO amount 0.85%, viscosity 21000 cps / 80 ° C,
A polyurethane prepolymer of 130000 cps / 20 ° C. is obtained. (2) Preparation of sealing material Except for using the polyurethane prepolymer of (1) above,
According to the same formulation components and procedure as in Example 1 / (2),
Two types of sealing materials "C-1" and "C-2" are prepared.

Comparative Example 1 (1) Synthesis of Polyurethane Prepolymer 3000 g of polyoxypropylene triol having a molecular weight of 5000 (manufactured by Asahi Glass Co., Ltd., 5030, trifunctional) 3000 g was put into a nitrogen-replaced reaction tank and under vacuum (10 mmHg or less). ) And dried under reduced pressure. After confirming that the water content was less than 0.05%, 546.5 g of MDI was added to this (NCO / OH =
2.41), adjust the temperature to 80 ± 5 ° C. and react for 1 hour. Then, 1 g of a 1% xylene solution of DBTDL was added and reacted at the same temperature for 2 hours to give a free NCO amount of 3.01.
%, Viscosity 11000 cps / 80 ° C, 31000 cps / 20
A polyurethane prepolymer at 0 ° C. is obtained. (2) Preparation of sealing material Except for using the polyurethane prepolymer of (1) above,
According to the same formulation components and procedure as in Example 1 / (2),
A sealing material "D-1" is prepared. Next, 500 g of the above-mentioned polyurethane prepolymer (1) was put into a nitrogen-substituted stirrer, and then dehydrated dioctyl phthalate 20.
After adding 0 g and stirring and dissolving for 10 minutes, 400 g of preliminarily dried carbon black and 200 g of calcium carbonate were gradually added, and after vacuum defoaming and stirring at 10 mmHg for 30 minutes, 50 g of xylene and a curing catalyst for viscosity adjustment. (0.3 g of 1% xylene solution of DBTDL) was added,
After vacuum degassing and stirring for 30 minutes, it is taken out into a sealed aluminum cartridge. This is designated as a sealing material "D-2".

Comparative Example 2 (1) Synthesis of Polyurethane Prepolymer Polyoxypropylene triol (3
2000 g of functional) and 1000 g of polyoxypropylene glycol having a molecular weight of 2000 (bifunctional) are put into a reaction tank purged with nitrogen, and dried under reduced pressure (10 mmHg or less) under vacuum. After confirming that the water content was below 0.05%, add 608 g of MDI to this (NCO / OH = 2.19),
The temperature is adjusted to 80 ± 5 ° C. and the reaction is carried out for 1 hour. afterwards,
Add 1 g of 1% xylene solution of DBTDL, and add 2 at the same temperature.
After reacting for a time, free NCO amount 3.1%, viscosity 1800
A polyurethane prepolymer of 0 cps / 80 ° C. and 45000 cps / 20 ° C. is obtained. (2) Preparation of sealing material Except for using the polyurethane prepolymer of (1) above,
According to the same formulation components and procedure as in Example 1 / (2),
A sealing material "E-1" is prepared. Next, except that the polyurethane prepolymer of (1) above is used, Comparative Example 1 /
Sealant "E-2" is prepared according to the same compounding ingredients and method as in (2).

[0024]Adhesion test  The sealing materials of Examples 1 to 3 and Comparative Examples 1 and 2 were
Subjected to the following tests (1) to (3), the results are shown in Tables 1 to 3 below.
You (1) Initial adhesive strength (initial viscosity) of a coated steel sheet with a width of 25 mm, a length of 100 mm and a thickness of 0.8 mm
At a place with a width of 10 mm from the tip, a 20 ° C x 65% RH atmosphere.
Melt coating of sealing material with a thickness of 5 mm under ambient atmosphere (80 ° C)
Glass with a width of 25 mm, a length of 50 mm and a thickness of 5 mm
Plates are overlapped and bonded, and after 10 minutes, pulling speed 50
Adhesive strength (Kg / cm) at mm / min or 200 mm / min²) Is measured
To do.

(2) Physical Properties of Rubber A sealing material having a thickness of 2 mm is melt-coated on a release paper (80
C.) and cured in a 20.degree. C., 65% RH atmosphere for 168 hours. Elongated according to JIS K 6301 dumbbell test
(%), Tensile strength (TS) (Kg / cm ² ) and hardness (Shore A type) are measured. Atmosphere conditions are normal (20 ° C x 6
5% RH), cold temperature (−30 ° C.) or hot (80 ° C.).

(3) Final strength (shear strength) As in the case of (1) above, the coated steel plate and the glass plate were adhered under the atmosphere of 20 ° C. and 65% RH (however, the glass plate was made by Sunstar Giken ( Co., Ltd. primer # 435-40,
(For the coated steel sheet, use Primer # 435-95 manufactured by the same company.) Then, leave it at room temperature for 7 days to complete moisture hardening, and then apply shear strength (Kg / cm ² ) at a pulling speed of 50 mm / min. The measurement is performed under the atmospheric condition of (2) above. CF indicates cohesive failure of the sealing material, and AF indicates interface failure between the primer / sealing material.

[Table 1]

[Table 2]

[Table 3]

Claims (1)

Claims: 1. A polyurethane prepolymer obtained by reacting an excess amount of a polyisocyanate compound with a polyether polyol having a hydroxyl group at the terminal and having a molecular weight of 6000 to 40,000, and a thermoplastic urethane multiblock. A reactive hot melt elastic sealant composition comprising a copolymer resin. 2. A polyurethane prepolymer content of 2
The reactive hot melt elastic sealant composition according to claim 1, which is 0 to 60% by weight. 3. The polyurethane prepolymer comprises a polyisocyanate compound NC to a polyether polyol.
The reactive hot melt elastic sealant composition according to claim 1 or 2, which is reacted so that the equivalent ratio of O / OH is 1.5 to 3.5. 4. The content of the thermoplastic urethane multi-block copolymer resin is 5 to 30% by weight.
The reactive hot melt elastic sealant composition according to any one of 1.