JP2830263B2 - Reactive hot melt adhesive - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a one-component reactive hot melt adhesive excellent in heat resistance, hydrolysis resistance and mechanical properties.

[Conventional technology]

Conventionally, a hot melt type and a reactive type are known as adhesives.

Hot-melt adhesive is applied to the adherend heated and melted with an applicator, solidified by cooling after laminating by pressure bonding, has an initial adhesive strength, and has the characteristic that workability is good. On the other hand, the adhesive strength at high temperatures decreases, and the range of use as an adhesive is limited. As hot melt adhesives, generally, ethylene-vinyl acetate copolymer (EVA) type, polyolefin type (low density polyethylene (LDPE), atactic polypropylene (APP), etc.),
Block copolymers (styrene-butadiene-styrene copolymer (SBS), styrene-isoprene-styrene copolymer (SIS), styrene-ethylene-butylene-styrene copolymer (SEBS), etc.), butyl rubber, polyamide And polyesters are commercially available. Of these, polyamide-based and polyester-based ones have relatively high heat resistance, but the coating temperature must be set high because of the melt viscosity and cannot be used for heat-sensitive adherends.

On the other hand, reactive adhesives have adhesive strength at high temperatures. However, the well-known epoxy, urethane,
A reactive adhesive such as acrylic has no initial adhesive strength at the time of operation, takes a long time to obtain an adhesive force by reaction hardening, and has poor workability.

For this reason, various reactive hot melt adhesives having both the initial adhesive strength of the hot melt type and the heat resistance of the reactive type have been studied. In this case, heating, oxidation,
Energy (electron beam or ultraviolet) irradiation, moisture / humidity, two-liquid, etc. have been proposed, but the one that is the simplest and is being put to practical use is one that is cured by moisture / humidity.
As such, isocyanate (hereinafter referred to as "
Reactive hot melt adhesives based on urethane prepolymers having an (NCO) group are known. For example, Japanese Patent Publication No. 51-47735 discloses a reactive hot melt adhesive mainly composed of an NCO-terminated urethane prepolymer composed of polypropylene glycol (PPG) and triene diisocyanate (TDI). Urethane having an ether structure as a skeleton has poor heat resistance.

JP-A-63-251415 discloses a reactive hot melt adhesive mainly composed of an NCO-terminated urethane prepolymer composed of polycaprolactone polyol, polyester polyol obtained from adipic acid and hexanediol, and diphenylmethane diisocyanate (MDI). Although disclosed, urethanes having a polyester skeleton cannot be used in applications requiring hydrolysis resistance.

Further, Japanese Patent Application Laid-Open No. 64-54089 discloses a reactive hot melt adhesive containing a polyalkylene diol or an NCO-terminated urethane prepolymer composed of a polyalkylene triol and an isocyanate as a main component, which has improved heat resistance. Although the strength of the adhesive itself is
Only 30 kg / cm ² (〜430 psi) or less was obtained, and higher mechanical strength was desired.

Further, as a polyurethane adhesive containing a polyhydroxy hydrocarbon polymer as a polyol component or as a curable polymer composition, for example, JP-A-56-55475 discloses a one-pack type adhesive using a blocked polyisocyanate. However, unlike NCO-terminated reactive hot-melt adhesives, this one needs 150
A heat treatment at 2 ° C. for 2 hours is required, resulting in poor workability, and a blocking agent remaining in the adhesive adversely affects heat resistance and mechanical properties. JP-A-57-83519 discloses a one-pack type curable polymer composition by adding a specific polyisocyanate compound. Heat work is required and workability is poor. Further, JP-A-60-173011, JP-A-64-2
Although polymer compositions are disclosed in 1215 and the like, these are two-pack types and have poor workability.

[Problems to be solved by the invention]

In view of the above, the present invention is to provide a one-part reactive hot-melt adhesive having good workability and mainly composed of an NCO-terminated urethane prepolymer having excellent heat resistance, hydrolysis resistance and mechanical properties. is there.

[Means for solving the problem]

The present inventors have conducted intensive studies to solve the above problems, and as a result, the average number of hydroxyl groups per molecule is 1 to 8, the number average molecular weight is 600 to 20,000, and the polyhydroxy hydrocarbon having an iodine value of 100 or less. One-component reactive hot-melt adhesive containing a urethane prepolymer having an NCO group at the molecular terminal by reacting a polyisocyanate with a diol having a molecular weight of less than 600 as a polyol component and reacting with a polyisocyanate I found

That is, the gist of the present invention is (A) a polyhydroxy hydrocarbon polymer having an average number of hydroxyl groups of 1 to 8 per molecule, a number average molecular weight of 600 to 2000, and an iodine value of 100 or less 95 to 50% by weight. % And a polyol component consisting of 5 to 50% by weight of a diol having a molecular weight of less than 600 and (B) a polyisocyanate.
A urethane prepolymer having 1 to 5% as a main component,
One-component reactive hot melt adhesive.

 Hereinafter, the present invention will be described in more detail.

The polyhydroxyhydrocarbon polymer used in the production of the urethane prepolymer has an average number of hydroxyl groups per molecule (hereinafter simply referred to as "number of hydroxyl groups") of 1 to 8 and a number average molecular weight of 600 to 20,000, Preferably 1000-2000
Those having an iodine value of 100 or less in the range of 0 are used. There is no particular limitation on the method for producing such a polyhydroxy hydrocarbon-based polymer, and after various vinyl monomers and diene-based monomers are polymerized by a known polymerization method such as radical polymerization, anionic polymerization, or cationic polymerization, and the terminal is hydroxylated. ,
If necessary, hydrogenation may be performed by a known method.

Other production methods include a method of oxidative decomposition and reduction of an isobutylene-diene monomer copolymer or an olefin (eg, ethylene, propylene, etc.)-Non-conjugated diene (or conjugated diene) copolymer.

Among them, hydrogenated polyhydroxydiene polymers are preferred.

The polyhydroxydiene-based polymer is produced by using a conjugated diene or a conjugated diene and a vinyl monomer as raw materials by a known method such as a radical polymerization method or an anion polymerization method. In the case of radical polymerization, if hydrogen peroxide is used as a polymerization initiator, a conjugated diene-based polymer or copolymer having a hydroxyl group at a direct terminal can be obtained.
In the case of anionic polymerization, a living polymer having a structure in which an alkali metal is bonded to a terminal is first produced using an anion polymerization catalyst, and then a monoepoxy compound, formaldehyde or the like is reacted and hydrolyzed. Raw conjugated dienes include isobutylene,
Chloroprene and the like can be used, but 1,3-butadiene is preferred. Examples of the copolymer component include vinyl monomers such as styrene, acrylonitrile, methyl (meth) acrylate, and vinyl acetate. The use amount of the copolymer component is preferably 30% by weight or less of the total monomer amount.

In addition, the polyhydroxydiene polymer is hydrogenated as necessary to improve heat resistance, but this reaction is performed using a catalyst such as nickel, cobalt, platinum, palladium, ruthenium, and rhodium alone or alone. What is necessary is just to carry out and to carry out and to carry out using hydrogen by a conventional method.

Here, in order to obtain sufficient heat resistance, the double bond contained in the polymer has an iodine value of 100 or less, preferably 5 or less.
It is desirably 0 or less, more preferably 20 or less.

In the present invention, a part of the polyhydroxyhydrocarbon polymer can be replaced with another polyol. Examples of other polyols include polyethylene glycol,
Polyalkylene glycols such as polypropylene glycol and polytetramethylene ether glycol, polycaprolactone polyols, polyester polyols such as castor oil-based polyols, lower polyols such as ethylene glycol and trimethylolpropane, or those obtained by adding propylene oxide or the like to these lower polyols And the like. The amount that can be substituted is 0 to 49% by weight of the polyhydroxyhydrocarbon polymer. Exceeding this range is not preferred because the heat resistance and hydrolysis resistance, which are the characteristics of the polyhydroxy hydrocarbon polymer, are poor.

The reason why the diol having a molecular weight of less than 600 is used in the present invention is to improve the mechanical properties of the obtained adhesive by increasing the molecular weight of the urethane prepolymer and increasing the urethane group concentration. Molecular weight 60 used in the present invention
Diols less than 0 include ethylene glycol, propylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 5-pentanediol, 1,
6-hexanediol, 2,5-hexanediol, 2-methyl-2,4-pentanediol, 3-methyl-2,4-pentanediol, 3-methyl-1,5-pentanediol,
1,7-hetanediol, 1,8-octanediol, 2-ethyl-1,3-hexanediol, 1,9-nonanediol,
1,10-decanediol, α-olefin glycol having 5 to 38 carbon atoms, hydroxymethylstearyl alcohol,
Alkylene diols such as dimer acid hydrogenated and reduced diol; polyethylene glycols having a molecular weight of less than 600, such as diethylene glycol and triethylene glycol; molecular weight 6
Ester diols having a molecular weight of less than 600, such as polypropylene glycols having a molecular weight of less than 00, polytetramethylene ether glycols having a molecular weight of less than 600, castor oil-based diols, polycaprolactone diol, and polymethylvalerolactone diol. Of these, preferred are alkylene diols, and particularly preferred are 1,2-butanediol, 3-methyl-1,5-pentanediol,
Diols having a branched chain such as 2-ethyl-1,3-hexanediol, α-olefin glycol having 5 to 38 carbon atoms, hydroxymethylstearyl alcohol, and hydrogenated and reduced dimer acid diol.

The amount of the diol having a molecular weight of less than 600 is 5 to 50% by weight of the polyol component. If the content is less than 5% by weight, the urethane prepolymer has only a low 100% tensile stress because the increase in the urethane group concentration of the urethane prepolymer is small.
On the other hand, if it is more than 50% by weight, flexibility is lost, and only low elongation can be obtained.

Note that a part of these diols can be replaced with a triol having a molecular weight of less than 600. Examples of triols include glycerin, trimethylolpropane, and triols having a molecular weight of less than 600 to which propylene oxide or the like has been added, but the amount that can be substituted is less than 50% by weight of a diol having a molecular weight of less than 600. Exceeding this range is not preferred because gelation tends to occur during the synthesis of the urethane prepolymer.

Next, as the polyisocyanate used in the present invention, tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI) and derivatives thereof,
Naphthylene diisocyanate, tolidine diisocyanate, isophorone diisocyanate, hexamethylene isocyanate, hydrogenated MDI, xylylene diisocyanate, and dimers and trimers of these diisocyanates can be used. Of these, TDI, MD
I.

There is no particular limitation on the method of the reaction between the polyol component and the polyisocyanate, and either the one-shot method or the prepolymer method can be employed.
% Need to be left. If the NCO group is less than 0.1%, only those having poor adhesion to the adherend can be obtained, while if it is more than 5%, flexibility is lost and only brittle materials can be obtained. For this purpose, although it depends on the raw materials used, it is usually possible to leave 0.1 to 5% of the molecular terminal NCO groups by performing the equivalent ratio of NCO group / OH group in the range of 1.01 to 4. Reaction temperature is from room temperature to 150 ° C
Preferably, the reaction can be suitably performed at 50 to 120 ° C. for a reaction time of about 10 minutes to 24 hours. If necessary, a catalyst such as dibutyltin dilaurate may be used.

Further, in the present invention, a tackifier resin may be added. As the tackifier resin, any of terpene, petroleum resin, rosin, and terpene phenol can be used.

Examples of the terpene-based tackifying resin include YS Resin A, YS Resin Px, YS Resin TO, and Clearon manufactured by Yasuhara Yushi Kogyo Co., Ltd., Piccolite A and Piccolite S manufactured by Hercules.
(Both are trade names). Examples of the petroleum resin-based tackifying resin include Alcon manufactured by Arakawa Chemical Industry Co., Ltd., Escolets manufactured by Tonen Petrochemical Co., Ltd., Hilets, Tack Ace, and Petrozine manufactured by Mitsui Petrochemical Co. (all are trade names). Examples of the rosin-based tackifying resin include Ester Gum and Super Ester (both are trade names) manufactured by Arakawa Chemical Industries, Ltd. Terpene
Examples of the phenolic tackifier resin include YS Polystar and Mighty Ace (all trade names) manufactured by Yasuhara Yushi Kogyo Co., Ltd. The amount of these additives is usually not more than 200 parts by weight, preferably not more than 150 parts by weight, based on 100 parts by weight of the urethane prepolymer as the main component. Further, waxes, plasticizers, elastomers, stabilizers and the like used in ordinary hot melt adhesives may be added.

〔The invention's effect〕

Since the reactive hot melt adhesive of the present invention is a one-part type, it can be heated and melted as it is, applied to an adherend, bonded and solidified to obtain an initial adhesive strength. Since the group reacts with moisture / moisture, the workability is good, and since it has a saturated hydrocarbon skeleton, it has excellent heat resistance and hydrolysis resistance. Further number average molecular weight 600
~ 20,000 polyhydroxy hydrocarbon polymer and molecular weight 600
Since less than the diol is used in combination, the mechanical properties after the end of the reaction effect are excellent and are extremely important in industry.

〔Example〕

Next, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples unless it exceeds the gist.

In the following Examples and Comparative Examples, the reaction hardening was confirmed according to JIS K6301 from a press sheet produced by sandwiching the synthesized adhesive with a Teflon sheet via a 2 mm thick spacer and pressing at 120 ° C. The obtained No. 3 dumbbell piece was used as a punched test piece, and the test piece was allowed to stand at a temperature of 23 ° C. and a relative humidity of 60%.
The reaction hardening was terminated when the physical properties became constant. The measurement of the adhesive force was based on JIS K6850. That is, an aluminum plate was used as the adherend, and the adhesive was pressed to produce a 0.2 mm-thick film in the same manner as described above, sandwiched between two aluminum plates, and held at 120 ° C. for 10 seconds. After pressing, it was rapidly cooled to obtain a test piece. The shear peel strength of the test piece after completion of the reaction hardening was measured. The number average molecular weight is
It was measured with a Vapor Pressure Osmometer.

Example 1 Polyether HA manufactured by Mitsubishi Chemical Corporation (trade name, hydroxyl equivalent:
0.877 meq / g number average molecular weight: 2000. 63.81 g of a polyhydroxyhydrocarbon polymer having an iodine value of 4.2) and AOGX68 manufactured by Daicel Chemical Industries, Ltd. (trade name, hydroxyl equivalent: 5.529 meq / g, α-olefin having 16 and 18 carbon atoms) Glycol) (15.18 g) was weighed into a polymerization tube equipped with a stirring blade, nitrogen introduction and a pressure reduction port, immersed in an oil bath at 80 ° C., and dried under reduced pressure for 2 hours. After the pressure in the system was restored with nitrogen, the product was Mate Kasei's Isonate 125M (trade name,
21.01 g of diphenylmethane diisocyanate)
The pressure was reduced again, and prepolymerization was performed at 80 ° C. for 3 hours. NCO groups remaining in the produced prepolymer were determined by titration to be 1.01%. Its tensile properties after completion of the reaction hardening were 100% tensile stress of 39.9 kg / cm ² , tensile strength of 98.9 kg / cm ² and elongation of 440%. Adhesive strength is 5
It was 5.4 kg / cm ² .

Examples 2 to 5 67 g of a tackifier resin shown in Table 1 was added to the prepolymer produced in the same manner as in Example 1, and the mixture was stirred and mixed at 120 ° C. The physical properties of the obtained pressure-sensitive adhesive are also shown in Table 1.

Example 6 36.04 g of polyether HA and 34.30 g of AOGX68 Isonate 1
The procedure was performed in the same manner as in Example 1 except that 25M was changed to 29.66 g. Table 1 shows the physical properties of the obtained adhesive.

Example 7 59.63 g of polyether HA and 14.19 g of AOGX68 Isonate 1
The procedure was performed in the same manner as in Example 2 except that 25M was changed to 26.18 g and Clearon P-105 (trade name, terpene) manufactured by Yasuhara Yushi Kogyo Co., Ltd. was used as a tackifier resin. Table 1 shows the physical properties of the obtained adhesive.

Example 8 21.47 g of polyether HA and 5.11 g of AOGX68 Isonate 12
Prepolymerization was performed in the same manner as in Example 1 using 9.43 g of 5M, and then Asahi Kasei Kogyo Co., Ltd. Tuftec H-1052 (trade name,
SEBS) Add 36.00 g of Clearon P-105 48.00 g and add 150
Stir and mix at ° C. Table 1 shows the physical properties of the obtained adhesive. (However, the pressing was performed at 150 ° C.) Examples 9 to 11 The same as Example 2 except that the components shown in Table 1 were used as diols having a molecular weight of less than 600, and the amounts of the respective components were similarly used in the amounts shown in Table 1. The same was done. Table 1 shows the physical properties of the obtained adhesive.
1 is also shown.

Example 12 Polytail H (trade name, hydroxyl equivalent: 0.83, manufactured by Mitsubishi Chemical Corporation)
1meq / g polyhydroxyhydrocarbon polymer having a number average molecular weight of 2800 and an iodine value of 1.0) 25.49 g, polyether HA 48.30 g, AOG
After drying under reduced pressure in the same manner as in Example 1 using 7.66 g of X68,
Prepolymerization was performed by adding 18.55 g of nate 125M.
67 g of Clearon P-105 was added to the resulting prepolymer.
The mixture was stirred and mixed at 120 ° C. The resulting adhesive had [NCO] = 0.91
%Met. The tensile properties after the reaction hardening were 100% tensile stress 28.8 kg / cm ² , tensile strength 63.9 kg / cm ² , and elongation 410%.

Comparative Examples 1,3 Polytail HA, AOGX68, Isonate 125M, Clearon P-1
05 was performed in the same manner as in Example 2 using the amounts shown in Table 1.
The physical properties of the obtained adhesive are also shown in Table 1.

Comparative Example 2 The same procedure as in Example 8 was carried out using polytail HA, Isonate 125M, Tuftec H-1052, and Clearon P-105 in the amounts shown in Table 1. Table 1 also shows the physical properties of the obtained adhesive.

Comparative Example 4 Polymer HA was replaced by Dimerdiol KX-500 (trade name, hydroxyl equivalent 3.617 meq / g, molecular weight 5) instead of Polytail HA
50. Dimer acid hydrogenated reduced diol) 29.95 g, AOGX68 29.3
The procedure was performed in the same manner as in Example 2 except that 8 g, 40 g of Isonate 125M, and 67 g of Clearon P-105 were used.

The obtained adhesive had [NCO] = 1.08%. After the reaction hardening, the tensile properties were as follows: tensile strength 80.4 kg / cm ² elongation 8%
Met.

When a diol having a molecular weight of less than 600 as in Comparative Examples 1 and 2 is not used, only those having low elongation or those having low 100% tensile stress can be obtained. These two were also unable to produce a test piece for measuring adhesive strength because the initial strength of the adhesive was too weak.

Even when a diol having a molecular weight of less than 600 is used in combination as in Comparative Example 3, if the added amount is less than 5% by weight of the polyol component, only a material having a low 100% tensile stress can be obtained and the adhesive strength is low.

When an alkylene diol KX-500 having a molecular weight of 550 is used instead of the polyhydroxyhydrocarbon polymer having a number average molecular weight of 600 to 20,000 as in Comparative Example 4, only an extremely low elongation can be obtained, resulting in lack of flexibility.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C09J 175/04-175/16 C08G 18 / 62,18 / 79

Claims (6)

(57) [Claims] (A) The average number of hydroxyl groups per molecule is from 1 to 8
Ke, number average molecular weight is 600 ~ 20000, iodine value is 100
(B) a polyisocyanate, which is obtained by reacting a polyol component consisting of 95 to 50% by weight of a polyhydroxy hydrocarbon polymer and 5 to 50% by weight of a diol having a molecular weight of less than 600 with the following isocyanate group: .
One-part reactive hot melt adhesive containing urethane prepolymer having 1 to 5% 2. The reactive hot melt adhesive according to claim 1, wherein the polyhydroxy hydrocarbon polymer has an iodine value of 50 or less. 3. The reactive hot melt adhesive according to claim 1, wherein the polyhydroxy hydrocarbon polymer has an iodine value of 20 or less. 4. The reactive hot melt adhesive according to claim 1, wherein the polyhydroxyhydrocarbon polymer is obtained by hydrogenating a double bond of polybutadiene polyol. 5. The reactive hot melt adhesive according to claim 1, wherein the diol having a molecular weight of less than 600 is an alkylene diol. 6. The reactive hot melt adhesive according to claim 1, wherein the reactive hot melt adhesive contains a tackifying resin.