JP2627839B2 - Reactive hot melt adhesive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyurethane reactive hot melt adhesive. More specifically, a temperature of 95
Quick solidification type capable melt coated at a low temperature of to 130 DEG ° C. ULE <br/> relates Tan based reactive hot-melt adhesive.

[0002]

2. Description of the Related Art Conventionally, hot melt adhesives are roughly classified into a hot melt type and a reaction type. Usually, the hot-melt type is made of a high-melting polymer such as EVA as a base resin, to which a tackifier or the like is added. The hot-melt type is applied to an adherend in a heated and melted state at about 150 ° C. and solidified by cooling. Excellent adhesive workability because adhesive force can be obtained in a short time. However, since it is based on a thermoplastic resin, the adhesive strength at high temperatures is significantly reduced, and the heat resistance is poor.

[0003] On the other hand, the reaction (curing) type is excellent in heat resistance because it is cross-linked and cured by a chemical reaction.
A large adhesive strength cannot be obtained from the initial stage unlike the hot melt type. These improved hot-melt type heat resistant polyester with improved, but polyamide-based hot melt adhesive or the like is also marketed, these 20
Melt coating at a high temperature close to 0 ° C. is required, and it is difficult to use it on an adherend having no heat resistance, such as plastic.

[0004] In response to these requirements, a so-called reactive hot-melt adhesive in which a crosslinking reaction is caused by some method after bonding to improve heat resistance is being developed.
As a reactive hot melt adhesive, for example, an ionic cross-linking type hot melt adhesive by a carboxyl group and a polyvalent metal ion in a polymer, an isocyanate group introduced into a molecular terminal or a side chain is blocked with a blocking agent such as caprolactam or phenol. There has been proposed a blocked isocyanate type hot melt adhesive and a moisture curing type hot melt adhesive in which an isocyanate group or an alkoxy group which reacts and crosslinks with water (moisture) is introduced into a polymer [Adhesion Technology Vol 19, No.2 (1990)] was not obtained.

[0005] However, the reactive hot-melt adhesive described above can be bonded in a short time like the conventional hot-melt adhesive, and is superior in heat resistance to the conventional hot-melt adhesive. Urethane reactive hot melt adhesive as particularly high overall characteristics, including the economy,
For example, JP-A-59-197432, JP-A-61-115
977, JP-A-62-181375, JP-A-2-305
881 and JP-A-2-305882.

[0006] Urethane-based reactive hot melt adhesives are:
A urethane prepolymer having an isocyanate group-containing molecular weight of several thousands is used as a base resin as a main component, and in some cases, a tackifier, a reactivity modifier, an antioxidant, a hydrolysis inhibitor, an antifoaming agent, an inorganic additive ( Filler) and the like. The isocyanate group contained in the prepolymer molecule contains water, bound water, OH group, CO
Reacts with active hydrogen groups such as OH groups and NH groups and moisture in the atmosphere, and generates bonds with high cohesive energy such as urea bonds and urethane bonds. It is said that. Such a urethane reactive hot melt adhesive reacts with an isocyanate group contained in a urethane prepolymer molecule as a main component, an active hydrogen compound of a base material and / or water (moisture) contained in an atmosphere or the like, and cures. By doing, it is superior in heat resistance compared to conventional hot melt adhesives,
Improvements in storage stability, initial adhesive strength development, open time, long-term durability and the like are strongly desired.

Polyurethane-based quick-setting reactive hot-melt adhesives that can be melt-coated at a low temperature and have a good rise in initial adhesive strength are highly crystalline, high-melting-point, high-molecular-weight polyols in which polyisocyanate and isocyanate group excess are used. It is common to use the isocyanate group-containing prepolymer having high crystallinity reacted as described above as the base polymer of the reactive hot melt adhesive.

[0008] However, such a polyurethane-based quick-setting type reactive hot-melt adhesive rapidly crystallizes and solidifies the resin upon application and cooling, and has very good initial adhesion. Since the initial bonding strength is given only by the property, the bending strength of the base material is strong in corner bonding and V-cut part bonding, and it is easy when stress (with heat generation) due to environmental temperature change or impact / shear force is applied May be peeled off. In addition, there is a case where shrinkage occurs due to crystallization, internal strain occurs, and delicate differences in pressure bonding conditions may cause peeling or insufficient adhesion, and improvement is desired.

For example, in the case of a glued plate, a metal plate, a corner bond between a plastic plate and a plastic or a metal, or a V-cut portion, if the bonding strength is not obtained within several seconds after bonding, the bending strength of the base material is strong. If the adhesive strength is not developed in a short time, the adhesive easily peels off, resulting in poor adhesion. Alternatively, the adhesive may be easily peeled off by an impact such as dropping before a strong adhesive force is developed due to a reaction (chemical bond) of an isocyanate group, which is a characteristic of the reactive hot melt adhesive, and poor adhesion may occur.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention have, we developed a fast setting type urethane reactive hot-melt adhesive which is excellent in long-term adhesion durability, be based polymer a polyurethane resin having a specific structure Thus, it is intended to obtain a urethane-based reactive hot melt adhesive having the following characteristics. (1) The bonding strength after bonding is fast rising. (2) Since the internal strain of the adhesive layer is small, the adhesive strength is large. (3) Quick solidification.

[0011]

That is, the present invention provides (A)
Polyester polyol (A ₁ ) containing an aromatic ring and / or a cyclo ring and having a melting point of 40 ° C. or higher, condensation of a linear alkylene diol having 4 or more carbon atoms with a linear alkylene dicarboxylic acid having 4 or more carbon atoms and / or a diester thereof. A soft segment containing a crystalline polyester polyol having a melting point of 50 ° C. or higher obtained from the reaction or a polyester polyol (A ₂ ) obtained by ring-opening polymerization of a lactone ring having a melting point of 40 ° C. or higher; One or more diols (B ₁ ) selected from the group of alicyclic diols,
A chain extender comprising one or more diols (B ₂ ) selected from the group of α, ω-alkylene diols having at least one side chain alkyl group at 0 or less (C) Organic polyisocyanate (A) , (B), and (C) as essential components, with an equivalent ratio of 0.3 ≦ (A ₁ ) / {(A ₁ ) + (A ₂ )} <
1.0 0.1 ≦ (B) / (A) ≦ 0.5 and 0.4 ≦ (B ₁ ) / {(B ₁ ) + (B ₂ )} ≦ 0.8 1.2 <(C) /{(A)+(B)}<2.5 isocyanate group-containing prepolymer having a isocyanate group content of 1.5 to 5.5% by weight. It is a mold hot melt adhesive.

The reactive hot-melt adhesive is 95-1.
It can be melt-coated at a low temperature of 30 ° C., and when cooled to about 60 ° C. or less, a high glass transition temperature due to (A ₁ ) and a crystallization due to (A ₂ ) and a component (B ₁ ) which raises the glass transition temperature rapidly due to the component (B ₁ ). It solidifies and gives an instant adhesive force due to cohesion due to concentrated urethane bonds formed by the chain of the chain extender (B) component and the isocyanate (C) component, but is introduced as a part of the essential component of the chain extender (B ₂ ). It shows initial tackiness for a short time due to the influence of the side chains of the components. Thereafter, the isocyanate group reacts with moisture or active hydrogen on the surface of the adherend, and the prepolymer having a molecular weight of several thousand is adhered by elongating and cross-linking the molecule while generating bonds with high cohesive energy such as urea bond and urethane bond. It develops strength and heat resistance.
These surprising effects (operability, strong initial adhesion and cohesion, final adhesion and heat resistance) are only manifested by the specific structure described above.

The components constituting the reactive hot melt adhesive of the present invention will be described below. The polyester polyol (A ₁ ) containing an aromatic ring and / or a cyclo ring and having a melting point of 40 ° C. or higher according to the present invention includes an aromatic ring diol, an alicyclic diol and an aromatic dicarboxylic acid, an alicyclic dicarboxylic acid, and an aromatic ring dicarboxylic acid. The raw material is at least one selected from the group consisting of acid anhydrides and alicyclic dicarboxylic anhydrides. A polyester polyol obtained by a condensation reaction between these diols and carboxylic acids.

As the aromatic diol and the alicyclic diol,
Specifically, bisphenol A (BPA), bisphenol S, para-xylene glycol, bis-hydroxyethoxy-benzene (BHEB), BPA or 1 to 5 mol adduct of bisphenol S with propylene oxide (PO) or ethylene oxide (EO) , Hydrogenated bisphenol A (HBPA), cyclohexane dimethanol (CH
DM) and the like. As aromatic dicarboxylic acid, alicyclic dicarboxylic acid, aromatic dicarboxylic anhydride and alicyclic dicarboxylic anhydride, specifically, terephthalic acid (TP
A), isophthalic acid (IPA), orthophthalic acid, 1,
5-naphthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride and the like can be mentioned.

The diols which can be used in combination are, for example, ethylene glycol, diethylene glycol 1,3-propylene glycol, 1,2-propylene glycol (1,2-propylene glycol).
PG), 1,4-butanediol (1,4-BD),
1,3-butanediol (1,3-BD), 1,5-pentanediol, 1,6-hexanediol (HD),
Neopentyl glycol (NPG), 3-methyl-1,
Examples thereof include diols such as 5-pentane glycol (3-MPD), 1,8-octanediol, and 1,9-nonanediol.

The dicarboxylic acids which can be used in combination are aliphatic dicarboxylic acids and oxycarboxylic acids having 5 to 12 carbon atoms. Specifically, the aliphatic dicarboxylic acids are glutaric acid, adipic acid (AA), pimelic acid, suberin Acids, azelaic acid, sebacic acid (SA) and the like. Examples of the oxycarboxylic acid include p-oxybenzoic acid and p- (hydroxyethoxy) benzoic acid. or,
The above acid anhydrides can also be used. These dicarboxylic acids may be used alone or in combination of two or more.

Specific polyester polyol (A ₁ )
In consideration of water resistance and durability, polyester polyols from HD and IPA, BD and AA / IPA, CH
Examples thereof include DM / AA, BD / CHDM and AA / IPA / TPA polyester polyols. Polyurethane resins obtained from these polyesters have high glass transition temperatures and are very hard at room temperature. For example, polyurethane resin from HD / IPA molecular weight 1000 and 4,4'-diphenylmethane diisocyanate (MDI) has a Tg of about 3
5 ° C.

A melting point of 50 obtained from a condensation reaction between a chain alkylene diol having 4 or more carbon atoms and a linear alkylene dicarboxylic acid having 4 or more carbon atoms and / or a diester thereof.
The crystalline polyester polyol (A ₂ ) having a temperature of at least
1,4-BD, HD, 1,8-octanediol, 1,
Very strong crystalline polyester polyols obtained by dehydration condensation of diols such as 9-nonanediol and AA, azelaic acid, SA, 1,10-decanoic acid, and 1,12-dodecadicarboxylic acid.

Polyester polyols such as poly (butylene adipate) diol and poly (hexylene adipate) diol used in the urethane industry have a melting point of 4%.
The temperature is 0 ° C. or higher, and urethane prepolymers using the same are different depending on the structure, but all of them are preferable because they have crystallinity due to the raw material polyester polyol and the initial adhesive strength is rapidly increased due to crystallization. In order to further accelerate the rise of the initial adhesive strength, a diol having a larger carbon number, for example, 1,8-octanediol,
1,9-Nonanediol and polyester polyols have a high melting point and a dicarboxylic acid giving crystallinity, for example, A
It is also preferable to use A, SA, 1,12-dodecanedicarboxylic acid or an aromatic ring or an alicyclic dicarboxylic acid exhibiting an initial adhesive force by giving a rigid structure, for example, phthalic acid or 1,4-cyclohexyldicarboxylic acid. It is an example. This is presumably because the urethane prepolymer obtained therefrom has high crystallinity and a high glass transition point (Tg), so that the molecular motion is restricted by cooling after coating, and the initial rise is further enhanced.

It is needless to say that a diol having a large number of carbon atoms is preferable from the viewpoint of hydrolysis resistance. However, it is a hot-melt field, which is a hot-melt field, and is mainly composed of an ether-containing diol having poor heat resistance and oxidation resistance. Is not preferred. A lactone-based polyester polyol having a melting point of 40 ° C. or higher obtained by ring-opening polymerization of a lactone ring refers to those obtained from caprolactone or δ-valerolactone using a diol such as ethylene glycol, diethylene glycol or NPG as an initiator and lactone esters. Diols mainly composed of lactone esters obtained by an exchange reaction with tetramethylene ether glycol or another polyester diol are also included in this.

The molar ratio of (A ₁ ) and (A ₂ ) is 0.1.
3 ≦ (A ₁ ) / {(A ₁ ) + (A ₂ )} <1.0. If it is less than 0.3, rapid solidification due to crystallization is mainly performed, so that the initial adhesive strength is reduced by the surrounding conditions (cooling rate,
(Pressing), and the characteristics are not uniform. (A) is a soft segment containing the above-mentioned polyester polyol as a main component, and may be blended and / or copolymerized into a soft segment within a range that does not impair the intended properties of the polyol other than the above-mentioned conditions. For example, a room temperature liquid or waxy sticky polyol having the same function as the tackifying component represented by (B ₂ ), for example, a glycol mainly composed of NPG and AA / I
Polyester polyol or the like obtained by dehydration condensation with PA may be blended within a range that does not impair the rapid solidification property.
The crystalline component (A ₁ ) preferably has a molecular weight of 2,000 or more from the viewpoint of ease of crystallization. If the molecular weight is less than 2,000, the crystallinity is small and the quick solidification is poor.

The melting point was measured by a differential thermal analyzer (heating rate 10 ° C. /
The value determined from the endothermic peak in (min) is used, but a value that is not much different from that obtained by other methods, for example, by a transmission-type melting point measuring device can be obtained. When the temperature is lower than 40 ° C., the expression of the initial adhesive strength, which is a feature of the present invention, is slow, and the operability, which is an advantage of the hot melt adhesive, is inferior.

The chain extender (B) of the present invention comprises at least one diol (B ₁ ) having a rigid structure selected from the group consisting of aromatic diols and / or alicyclic diols,
0 or less, one or more diols selected from the group of α, ω-alkyl diols having at least one side chain alkyl group (B
₂ ) Consists of One or more diols selected from the group of aromatic ring diols and / or alicyclic diols defined as (B ₁ ) are specifically BPA, bisphenol S, paraxylene glycol, BHEB, BPA or bisphenol PO or EO 1 to 5 mol adduct of S, HBPA, CH
DM and the like.

As one or more glycols selected from the group of α, ω alkylenediols having 10 or less carbon atoms and having at least one side chain alkyl group defined as (B ₂ ), specifically, 2-PG, 1,3-BD, NPG,
3-MPD, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol,
2,2-diethyl-1,3-propanediol, 2-n
-Butyl-2-ethyl-propanediol and the like. The base polymer of the urethane-based reactive hot melt adhesive generally uses only a linear polyol in order to increase the crystallinity and speed up the initial rise.

The urethane reactive hot melt adhesive introduced from the diol or dicarboxylic acid of the present invention is:
(A) Polyester polyol (A ₁ ) containing an alicyclic ring such as an aromatic ring and / or a cyclo ring and having a melting point of 40 ° C. or higher, a linear alkylene diol having 4 or more carbon atoms and a linear alkylene dicarboxylic acid having 4 or more carbon atoms And / or a crystalline polyester polyol having a melting point of 50 ° C. or higher obtained from a condensation reaction with a diesterified product thereof or a lactone-based polyester polyol (A ₂ ) obtained by ring-opening polymerization of a lactone ring at 40 ° C. or higher as a soft segment; A specific action is exhibited by using a diol having a rigid structure (rigid diol) (B ₁ ) and a short-chain diol (branched diol) (B ₂ ) into which a side chain is introduced as a chain extender.

The rigid diol (B ₁ ) gives the reactive hot melt adhesive an appropriate hardness and an increase in Tg. An appropriate increase in hardness and Tg is an essential component for increasing the initial rise and increasing the initial adhesive strength because the molecular motion of the adhesive is restricted by cooling after coating. Branched diol
(B ₂ ) is an essential component for imparting a suitable initial tackiness to the reactive hot melt and for alleviating internal strain generated in the adhesive layer due to a rapid rise of the initial tackiness.

The ratio (B) / (A) of the chain extender to the soft segment is 0.1 ≦ (B) / (A) ≦ 0.5. When (B) / (A) is less than 0.1, the initial rise is very fast but the amount of the branched diol which is effective for strain relaxation is small, so that the internal strain cannot be relaxed by crystallization or vitrification. However, if it receives a stress or impact from the inside immediately after bonding, it may cause peeling, which is not preferable. When a chain extender is introduced beyond 0.5, (B ₁ )
/ ((B ₁ ) + (B ₂ )) ratio, but the hardness, Tg and the amount of side chains introduced of the reactive hot melt adhesive are increased, the initial tackiness is sufficient, and the internal strain is relaxed. Although the resulting impact resistance is excellent, the crystallization rate is extremely reduced, and the rise of the adhesive force, which is the object of the present invention, is slow, and the workability as a quick-setting urethane-based reactive hot-melt adhesive is poor and unsuitable. In addition, the urethane group concentration is increased, the melt viscosity is high, and the operability is poor.

The ratio between the rigid diol (B ₁ ) and the branched diol (B ₂ ) of the present invention is 0.4 ≦ (B ₁ ) / ｛(B ₁ ) +
(B ₂ )｝ ≦ 0.8. If it is less than 0.4, the ratio of the rigid diol in the whole chain extender is small, and the Tg of the adhesive layer is low.
In addition, instantaneous adhesive strength immediately generated by cooling, which is considered to depend on hardness, is low. If it exceeds 0.9, the instantaneous force is higher than the bending strength of the substrate, but the tackiness is insufficient. It is considered that the scope of the present invention is a range where the initial tackiness is also provided and the instantaneous adhesive strength is comparable to the bending strength of the substrate.

An unbranched alkylene linear diol such as 1,4-BD used as a chain extender in a general urethane resin may be used as an extender in combination with the rigid diol and the branched diol represented by (B). In this case, the total amount of the chain extender is polyol (A).
Should not exceed about 0.8. If it exceeds about 0.8, the melt viscosity becomes high, and the melt coating becomes difficult at a low temperature of 95 to 130 ° C. which is a feature of the present invention.

As the organic isocyanate (C) of the present invention, tolylene diisocyanate (TDI), xylylene diisocyanate, MDI, 4,4'-diphenyl ether diisocyanate, 2-nitrodiphenyl-4,4 '
-Diisocyanate, 2,2'-diphenylpropane-
4,4'-diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, 4,4 '
Aromatic diisocyanates such as -diphenylpropane diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, naphthylene diisocyanate, 3,3'-dimethoxydiphenyl-4,4'-diisocyanate, tetramethylene diisocyanate,
Hexamethylene diisocyanate (HDI), aliphatic diisocyanates such as lysine diisocyanate, isophorone diisocyanate (IPDI), hydrogenated tolylene diisocyanate, aliphatic diisocyanate hydrogenated diphenylmethane diisocyanate (H ₁₂ MDI), etc. or the like,
Polymeric polyisocyanate which is a polyisocyanate having an isocyanate group obtained by the reaction of a polymer of these diisocyanates or difunctional or higher functional polyols and the above-mentioned diisocyanate compound and the polymer, a polyol adduct of isocyanate, uretdione, Isocyanurates and carbodiimide modified products are also included. Particularly preferred are aromatic diisocyanates such as MDI, PPDI and TDI and H ₁₂ MDI from the standpoint of rising initial adhesive strength and durability of the adhesive layer.

The reactive hot-melt adhesive according to the present invention must contain an isocyanate group which reacts with active hydrogen and moisture in the molecule, and the equivalent ratio of hydroxyl group to isocyanate group (NCO / OH), that is, ( C) /
It is preferable that {(A) + (B)} is 1.2 to 2.5 and the isocyanate group content is 1.5 to 5.5% by weight. When (C) / {(A) + (B)} is 1.2 or less, the heat resistance of the adhesive layer is inferior, and the molecular weight is too large, the viscosity in the molten state is too high, and the operability is lacking. If it exceeds 2.5, unreacted diisocyanate remains, so that there is an odor of diisocyanate at a high temperature, and the activity of the diisocyanate monomer is high, so that the viscosity stability in a high-temperature molten state is not preferable. On the other hand, if the isocyanate group content is 1.5% or less, the molecular weight increases, and the viscosity in the molten state is too high, resulting in poor operability. If it is 5.5% or more, the molecular weight is too small, which hinders operation with a roll coater. In addition, the initial strength is low, the improvement of the adhesive strength by the reaction with active hydrogen and moisture is slow, and the adhesive layer is undesirably peeled off by impact.

The isocyanate group-containing polyurethane prepolymer used in the reactive hot melt adhesive according to the present invention can be produced by a known method, for example, a bulk polymerization (bulk polymerization) method in which the reaction is carried out in a molten state. For example, in an inert gas atmosphere such as nitrogen, a reactor having a strong stirring device and a heating device, a kneader / ruder,
Examples thereof include a method of performing a heat-melting reaction with a kneader such as a Hensiel mixer and a Nauter mixer, and a method of manufacturing with an excluder.

In producing the polyurethane prepolymer according to the present invention, a catalyst and a stabilizer can be used if necessary. As the catalyst, for example, triethylamine,
Examples include nitrogen-containing compounds such as triethylenediamine, and organic metal compounds such as dibutyltin dilaurate, tin octylate, and zinc stearate. As the stabilizer, for example, an ultraviolet absorber such as a substituted benzotriazole, an antioxidant such as a phenol derivative, a hydrolysis inhibitor, and a so-called retarder for controlling a reaction of an isocyanate group can be added.

The reactive hot melt adhesive of the present invention comprises an isocyanate group-containing polyurethane polymer as a main component. If necessary, an isocyanate and a non-reactive filler, tackifier and thermoplastic resin having an affinity therewith are used. May be added in a range of 10% by weight or less. These additives may be added and mixed at the time of production of the prepolymer or as a prepolymer. It is preferable that the tackifier and the thermoplastic resin are mixed with the branched diol (B ₂ ) , heated and dissolved to form a uniform state, and then reacted with the organic diisocyanate. As the filler, one or two selected from magnesium oxide, silica powder, calcium carbonate, carbon black, titanium oxide, metal powder, etc.
And dry fillers of at least one species. Typical tackifiers include (hydrogenated) rosin ester derivatives, petroleum resins, terpene resins, cumarone-indene resins, xylene resins, ketone resins, and the like, and thermoplastic resins such as thermoplastic polyurethane resins, polyester resins, and ethylene resins. -Methyl acrylate resin and the like, and these can be used alone or as a mixture of two or more.

According to the present invention, a hot-melt adhesive of 95 ° C. to 130 ° C. can be melt-coated at a low temperature,
And because it has an initial tackiness and has a bondable time of several minutes to tens of minutes, rigid PVC, acrylic plate, ABS,
It is suitable for bonding of plastics having no heat resistance such as polypropylene and bonding of the above-mentioned plastics and the like to aluminum, steel, paper, wood, etc., and particularly for bonding of these large members.

[0036]

The present invention will be described below with reference to specific examples. The components, ratios, operation orders, and the like shown below can be changed without departing from the spirit of the present invention. "Parts" and "%" in the examples are "parts by weight" and "% by weight" unless otherwise specified.

Example 1 A polyester polyol (abbreviated as PHIPA-1000) from HD and IPA was placed in a reaction vessel equipped with a thermometer, a cooling device, a reduced-pressure dehydrator and a stirrer.
500 parts, (0.5 mol), polyester polyol from 1,4-BD and AA (abbreviated as PBA-2500; hydroxyl value 44.9, molecular weight 2500, melting point 52.5 ° C.) 1250 parts, (0.50
Mol), 15.2 parts (0.07 mol) of BPA, NPG
8.3 parts (0.08 mol) were charged, dehydrated by vacuuming at 110 ° C., then cooled, and MDI 605.
6 parts (2.42 mol) were added. The reaction generates heat and the viscosity rises sharply, but it is cooled to keep the internal temperature at about 90 ° C. The reaction was maintained for 4 hours at this temperature. The structural factor of the obtained prepolymer was (A ₁ ) / (A) = 0.50,
(B) / (A) = 0.15, (B ₁ ) / ｛(B ₁ ) +
(B ₂ )｝ = 0.46, (C) / ｛(A + B｝ = 2.1
1, NCO content 4.5%, viscosity = 20,000 mP
a · s / 100 ° C. Clamping pressure 0.1kg / within 30 seconds using steel plate and rigid PVC (PVC) as adherend
The adhesive was adhered under the conditions of cm ² and a pressing time of 1 minute, and the properties as a hot melt adhesive were measured. Tack free time = 3
Minute, instantaneous adhesion = ◎, impact resistance = ◎, softening point (after 7 days)
= 185 ° C., which were satisfactory values for instantaneous tackiness, impact resistance, and curability.

Example 2 A kneader equipped with a thermometer, a cooling device, and a vacuum dehydrating device was provided with an HD.
And IPA / TPA / AA = 20/30/50 (molar ratio)
Polyester polyol (abbreviated as PH-1000) having a hydroxyl value of 112.2, a molecular weight of 1,000, and a melting point of 85.
(1 ° C.) 500 parts (0.50 mol), polyester polyol from HD and AA (abbreviated as PHA-2000; hydroxyl value 56.1, molecular weight 2000, melting point 54.0 ° C.) 10
00 parts (0.50 mol), hydrogenated bisphenol A35.
4 parts (0.15 mol) and 10.4 parts (0.10 mol) of NPG were charged, dehydrated by vacuuming at 110 ° C., cooled, and then cooled at 60 ° C. or less to a Millionate MTL (carbodiimide modified by Nippon Polyurethane Industry Co., Ltd.). Isocyanate
(NCO content = 29%) 542.2 parts were added. Heat is generated by the reaction and the viscosity rises sharply, but it is cooled to keep the internal temperature at about 100 ° C. The reaction was maintained for 4 hours at this temperature. The structural factor of the obtained prepolymer is (A ₁ ) /
(A) = 0.50, (B) / (A) = 0.25,
(B ₁ ) / {(B ₁ ) + (B ₂ )} = 0.60, (C)
/{(A)+(B)}=1.50, NCO content = 2.
5%, viscosity = 50,000 mPa · s / 100 ° C. Tack-free time = 2 minutes, instant adhesiveness = ◎, impact resistance = ◎, softening point (after 7 days) = 205 ° C., which were satisfactory values for instantaneous tackiness, impact resistance, and curability.

Examples 3 to 7 Using the same apparatus and method as in Example 1, prepolymers were produced with the molar ratios shown in Table 1. Table 1 shows the properties of the prepolymer and the results obtained by using a roll coater (a test coater manufactured by Matsushita Industries).

[0040]

[Table 1]

Comparative Examples 1 to 5 Using the same apparatus and method as in Example 1, prepolymers were produced at the molar ratios shown in Table 2. Table 2 shows the properties of the prepolymer and the results obtained using a roll coater (test coater manufactured by Matsushita Kogyo).

[0042]

[Table 2]

The properties and results were determined by the following methods. Viscosity: Measured with a B-type rotational viscometer. mPa · s / 100 ° C. Tack-free time: Sampled from a roll coater set at 110 ° C, and applied to a glass plate at room temperature (25 ° C) with a bar coater heated to 100 ° C at an application amount of 75 g / m ² . Immediately start measuring the tactile tack, and let the time when the tack disappears be the tack free time (minutes). The tack-free time is a relative evaluation value of the bondable time. Initial adhesion: 50 g / m ² applied to a 300 mm wide x 1000 mm long steel plate by a Matsushita test coater using a roll coater set at 110 ° C, and after 5 minutes, rigid PVC (PVC) is adhered. Sample. For the initial adhesive strength, a sample having a width of 25 mm is cut out after 3 hours, and the tensile shear strength (Kg / cm ² ) is measured with Tensilon. Adhesive strength after 7 days: The above laminated sample was left at 25 ° C. for 7 days, and then the tensile shear strength (Kg / cm ² ) was measured. SP (softening point): Prepared by the same method as used for tack-free measurement. After the film sample is left for a predetermined number of days, the film is heated at a rate of 10 ° C./min under a load of 5 g / 100 μm, and the softening point (° C.) is reached at the temperature at which the film rapidly expands.

[0044]

The quick-setting urethane-based reactive hot melt adhesive of the present invention is excellent in long-term adhesion durability and has the following characteristics by using a polyurethane resin having a specific structure as a base polymer. (1) The bonding strength after bonding is fast rising. (2) Since the internal strain of the adhesive layer is small, the adhesive strength is large. (3) Quick solidification.

Claims (1)

(57) [Claims] 1. A polyester polyol (A ₁ ) containing an aromatic ring and / or a cyclo ring and having a melting point of 40 ° C. or higher,
A crystalline polyester polyol having a melting point of 50 ° C. or more or a lactone ring having a melting point of 40 ° C. or more obtained from a condensation reaction between a linear alkylene diol having 4 or more carbon atoms and a linear alkylene dicarboxylic acid having 4 or more carbon atoms and / or a diester thereof. Polyester polyol (A) obtained by ring-opening polymerization of
₂ ) a soft segment mainly comprising (B) (B) one or more diols (B ₁ ) selected from the group of aromatic ring-containing diols and / or alicyclic diols and 10 carbon atoms
In the following, one or more diols selected from the group of α, ω-alkylene diols having one or more side chain alkyl groups (B
Consisting ₂₎ a chain extender represented by (C) an organic polyisocyanate (A), (B), (a C) as essential components, an equivalent ratio _{0.3 ≦ (A 1) / {} (A 1) + (A ₂ )｝ <
1.0 0.1 ≦ (B) / (A) ≦ 0.5 and 0.4 ≦ (B ₁ ) / {(B ₁ ) + (B ₂ )} ≦ 0.8 1.2 <(C) /{(A)+(B)}<2.5 isocyanate group-containing prepolymer having a isocyanate group content of 1.5 to 5.5% by weight. Mold hot melt adhesive.