JPH0551573A - Hot-melt adhesive - Google Patents

Abstract

PURPOSE:To prepare a moisture-curable hot-melt urethane adhesive excellent in initial adhesion. CONSTITUTION:A moisture-curable hot-melt adhesive comprising an isocyanate- termrinated urethane prepolymer is prepd. by reacting a crystalline aliph. polyester diol prepd. by reacting sebacic acid and 1,6-hexanediol, an arom. polyester diol prepd. by reacting isophthalic acid, terephthalic acid, neopentyl glycol, and 1, 6-hexanediol, and diphenylmethane diisocyanate. The adhesive is melted at 100 deg.C and applied to a plywood to stick an aluminum foil thereto. The combined use of the crystalline aliphatic polyester diol and the arom. polyester diol server to improve remarkably the initial adhesion.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to hot melt adhesives.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication (Kokai) No. 62-18137 discloses a hot melt adhesive comprising a urethane resin containing isocyanate groups at both ends, which is obtained by reacting a crystalline aliphatic polyester diol with a diisocyanate.

On the other hand, a hot melt adhesive composed of a urethane resin containing isocyanate groups at both ends, which is obtained by reacting an aromatic polyester diol with a diisocyanate, is also known.

[0004]

However, if the above hot-melt adhesives are used alone,
In any case, there is a drawback that the initial adhesiveness is poor.

[0005]

The inventors of the present invention have made extensive studies in view of the above-mentioned circumstances and found that a polyol mixture obtained by using a crystalline aliphatic polyester diol in combination with an aromatic polyester diol is reacted with polyisocyanate. Which has excellent initial adhesiveness when a mixture of a cured product of a crystalline aliphatic polyester diol and a polyisocyanate and a mixture of a reacted product of an aromatic polyester diol and a polyisocyanate is used. The inventors have found that it can be used as a melt adhesive and completed the present invention.

That is, according to the present invention, a urethane mixture containing isocyanate groups at both terminals is prepared by reacting a polyol mixture of a crystalline aliphatic polyester diol (A) and an aromatic polyester diol (B) with a diisocyanate (C). A hot-melt adhesive and a crystalline aliphatic polyester diol (A) and a diisocyanate (C) reacted with an isocyanate group-containing urethane resin at both ends, and an aromatic polyester diol (B) and a diisocyanate (C). It is intended to provide a hot melt adhesive containing a reacted urethane resin containing isocyanate groups at both ends.

The hot melt adhesive of the present invention is roughly classified into the following two types. Crystalline aliphatic polyester diol (A) [hereinafter,
It is called diol (A). ] And an aromatic polyester diol (B) [hereinafter referred to as diol (B). ] A urethane mixture containing isocyanate groups at both ends, which is obtained by reacting a polyol mixture with the above and a diisocyanate (C). Urethane resin containing isocyanate groups at both ends obtained by reacting diol (A) and diisocyanate (C) [hereinafter referred to as prepolymer (A). ], And diol (B)
Urethane resin containing isocyanate groups at both ends [hereinafter referred to as prepolymer (B)] obtained by reacting an isocyanate group with a diisocyanate (C). ] Consisting of a mixture with.

Next, a method for producing the urethane resin containing isocyanate groups at both ends used in the above-mentioned and the adhesive will be sequentially described. The urethane resin used in the above-mentioned adhesive of the present invention can be obtained by previously mixing the diol (A) and the diol (B) and reacting this with the diisocyanate (C).

The diol (A) must have crystallinity. Whether the crystallinity shows a sharp peak of crystallization heat or heat of fusion in a thermal analysis such as DSC,
Alternatively, it can be easily measured depending on whether or not it shows a crystal structure by X-ray analysis. For example, when the crystallinity is measured by DSC thermal analysis, it is preferable that the diol (A) has a heat of fusion of 30 millijoules / mg or more. More simply, it can be distinguished from others by whether it is solid at room temperature.

The preferred diol (A) is at least one compound selected from the group consisting of linear aliphatic dicarboxylic acids, aliphatic dicarboxylic acid dialkyl esters and linear aliphatic saturated dicarboxylic acid anhydrides, and linear fatty acids. Examples thereof include a polyester diol obtained by a polycondensation reaction with a group saturated diol or a polyester diol obtained by a ring-opening polymerization reaction of ε-caprolactone.

Examples of the straight-chain aliphatic saturated diol which can be used for the synthesis of the diol (A) include ethylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1, 10-decanediol, 1,12-dodecanediol, 1,20-
Examples of the straight-chain aliphatic saturated dicarboxylic acid component such as eicosane diol include succinic acid, adipic acid, azelaic acid, sebacic acid, 1,16-hexadecanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,20- Eicosane dicarboxylic acid, succinic anhydride, adipic anhydride,
Examples thereof include azelaic acid anhydride, 1,10-decanedicarboxylic acid anhydride, sebacic acid diethyl ester, 1,12-dodecanedicarboxylic acid diethyl ester, and 1,20-eicosanedicarboxylic acid dimethyl ester. Examples of the lactone polyester diol include ε-caprolactone. These diols and dicarboxylic acids may be used alone or in combination of two or more. The number average molecular weight of the diol (A) is not particularly limited, but is usually 500 to 5,000.

Examples of the diol (B) include polyester diols obtained by polycondensation using a compound having an aromatic ring structure as a diol component and / or a dicarboxylic acid component as an essential component. Diol (B)
Examples of the diol having an aromatic ring structure that can be used for synthesizing bisphenol A include ethylene oxide adduct of bisphenol A, propylene oxide adduct of bisphenol A, ethylene oxide-propylene oxide random adduct of bisphenol A, and ethylene oxide of bisphenol A. Examples of the dicarboxylic acid in which the propylene oxide block adduct has an aromatic ring structure include isophthalic acid, terephthalic acid, dimethyl isophthalate, and diethyl terephthalate. The diol (B) may be used alone or in combination of two or more diols having different structures or different molecular weights.

The number average molecular weight of the diol (B) is not particularly limited, but is usually 5,000 to 40,000, and one having a high molecular weight is preferable. The diol (B) may be a diol having an aromatic ring structure or a dicarboxylic acid having an aromatic ring structure, which has been subjected to a polycondensation reaction only as an essential component, but may have an aromatic ring structure if necessary. A polycondensation reaction may be carried out by using a diol or dicarboxylic acid which is not used.

Other raw materials that can be used in this case include linear aliphatic saturated diols and linear aliphatic saturated dicarboxylic acids that can be used in the production of the above diol (A), and also, for example, 1,3- Propanediol, 1,5-
Examples include diols such as pentanediol, neopentyl glycol and 3-methylpentanediol, glutaric acid, suberic acid and glutaric acid dimethyl ester.

The diol (B) may be used as it is, but it is preferable to use it in a higher molecular weight form. As a method of polymerizing, for example, a method of further reacting with a diisocyanate (C) described below to obtain an aromatic polyester diol having a urethane bond in a higher molecular weight molecule is mentioned.

Examples of the diisocyanate (C) include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, 1,5-naphthylene diisocyanate, hydrogenated diphenylmethane diisocyanate, isophorone diisocyanate, Examples include carbodiimidated diphenylmethane diisocyanate.

The urethane resin is obtained by reacting a mixture of diol (A) and diol (B) with diisocyanate (C). If necessary, an amorphous diol other than diol (A) and diol (B) is used. Can be used together.

The amorphous diol can be easily obtained by using the raw materials exemplified in the above diols (A) and (B). Other examples include lactone polyester diols using β-methyl-δ-valerolactone as a raw material, polyether polyols which are polymers of alkylene oxides, polybutadiene polyols, acrylic polyols and the like.

Whether or not it is an amorphous diol can be easily understood by measuring the heat of fusion by DSC thermal analysis. It can be more simply distinguished by whether or not it is liquid at room temperature. When the amorphous diol is used, the urethane resin finally obtained has a long open time, can be used without being activated by heat again, and can have a smaller viscosity.
The workability is improved.

It is necessary to select the usage ratio of each polyester diol in consideration of the open time, melt viscosity, etc., but in the two-component system of diol (A) and diol (B), diol (A) and (B) are used. When the total of 100 parts by weight is 100 parts by weight, the diol (A) is 20 to 80 parts by weight, and in the three-component system using the diol (A), the diol (B) and the amorphous diol, the above-mentioned two-component diol (A) is used. It is desirable that the amount of the amorphous diol is 20 to 50 parts by weight when the total of the diol and the diol (B) is 100 parts by weight.

As a method of producing the above-mentioned urethane resin containing terminal isocyanate group, a mixture containing diol (A) and diol (B) as essential components and diisocyanate (C) are mixed with a hydroxyl group and an isocyanate group in excess of isocyanate group. The method of reacting below is mentioned.

Reaction conditions other than those mentioned above are not particularly limited, but usually, in the presence of an inert gas, a polyol mixture is added dropwise to the diisocyanate (C) as necessary, or the diisocyanate (C) is added to the polyol mixture. It may be added and reacted until the isocyanate group becomes constant. However, since this reaction is an isocyanate-excessive reaction, it is usually a mild reaction condition, for example, 6
It is preferable to react at 0 to 80 ° C. for 1 to 10 hours. As the catalyst, an organometallic or amine-based catalyst generally used for urethane resin is preferable.

When a catalyst is used, it is desirable to add it in consideration of heat stability and moisture curability when used as an adhesive. The urethane resin used for one of the adhesives is a mixture of the prepolymer (A) and the prepolymer (B) (hereinafter referred to as a urethane resin mixture). When the raw materials used are the same, it is preferable to use the same as the above-mentioned adhesive, because higher initial adhesiveness can be expected.

The reaction conditions similar to those described above can be adopted for the respective methods for producing the urethane resin. The urethane resin mixture (1) is further prepared by reacting an amorphous diol with a diisocyanate (C), and a urethane resin containing isocyanate groups at both ends [hereinafter referred to as prepolymer (C)]. ] Can also be contained. In this case, there is an effect that the open time of the adhesive can be made longer and a high degree of initial adhesiveness can be expected.

In the case of the adhesive of (2), the mixing ratio of the prepolymers (A) and (B) in the two-component system is 100 parts by weight of the prepolymers (A) and (B). In the three-component system in which (A) is 20 to 80 parts by weight and the prepolymer (A), the prepolymer (B) and the prepolymer (C) are used, the above two-component prepolymer (A) and the prepolymer (B) are used. It is desirable to set the prepolymer (C) to 20 to 50 parts by weight when the total of the above is 100 parts by weight.

The adhesive of the present invention has a melt viscosity of 5000 to 100000 CPS at 100 to 130 ° C.,
It is preferable to carry out the mixing or the reaction so that the content of the isocyanate group is 0.5 to 4% by weight of the obtained urethane resin.

The urethane resin obtained in the present invention may be used in combination with a resin such as an ethylene-vinyl acetate copolymer which has been conventionally used as a hot melt base resin. Further, if necessary, to the extent that the performance of the adhesive is not impaired, auxiliary materials and additives used for ordinary adhesives, such as plasticizers and pigments,
It is also possible to use thermoplastic polymers, moisture scavengers, storage stabilizers, antiaging agents and the like.

The adhesive of the present invention includes calcium carbonate,
Inorganic fillers such as magnesium oxide, talc, barium sulfate, kaolin clay, and glass balloons, and organic fillers such as Teflon powder can be added as long as they do not hinder the viscosity and the adhesiveness.

In the present invention, the initial adhesive strength means that after the molten hot melt adhesive is applied to one adherend and then the other adherend is pasted, the hot melt adhesive solidifies and adheres. It is the adhesive force during a very short time during the process of developing force.

The adhesive of the present invention can be used as a solvent-type adhesive by dissolving it in an organic solvent, if necessary.

[0031]

EXAMPLES The present invention will now be described with reference to examples. Less than,
Unless otherwise specified, "part" means part by weight and "%" means% by weight.

Reference Example 1 [Synthesis of diol (A)] A 2 liter flask set in a dehydration circuit was charged with 395 parts of 1,6-hexanediol and 605 parts of sebacic acid, and 0.05 g of tetraisopropyl titanate was added.
Condensation was performed at a temperature of 220 ° C. until the acid value was 1.0% or less and the water content was 0.06% by weight or less to obtain a diol (A-1).

Reference Examples 2 to 3 [Synthesis of diols (B) to (C)] As shown in Table 1, the same procedure as described above was carried out except that the kinds and amounts of the diol and dicarboxylic acid used were changed. hand,
A diol (B-1) and a diol (C-1) were obtained, respectively.

[0034]

[Table 1]

Reference Example 4 [Synthesis of urethane bond-containing aromatic diol (B)] Polyester polyol 87.3 obtained by reacting 287 parts of isophthalic acid, 287 parts of terephthalic acid and 426 parts of neopentyl glycol in the same manner as above. In the presence of 50 ppm of dibutyltin dilaurate, 12.7 parts of 143 L of isonate [liquid diphenylmethane diisocyanate manufactured by Mitsubishi Kasei Co., Ltd.] is added dropwise at 80 ° C., and reacted at 80 ° C. until the isocyanate content becomes 0%, A diol (B-2) was obtained.

This diol (B-2) is a pale yellow solid and has a hydroxyl value of 7.5, an acid value of 0.6 and a number average molecular weight of 150.
It was 00. Example 1 A reflux circuit was set and air was previously replaced with nitrogen gas.
Add diol (A-1) 50 to a 4-liter 4-necked flask.
Parts and 50 parts of diol (B-1) were added, 50 ppm of dibutyltin dilaurate was added, and the mixture was heated to 80 ° C. to uniformly dissolve it, and then 143 L of isonate was added at 80 ° C.
Was added dropwise and the reaction was carried out at the same temperature until the isocyanate content became constant. After that, degassing is performed under reduced pressure 1
It was taken out at 00 ° C. to obtain a urethane resin (P-1).

The properties and adhesive properties of the urethane resin (P-1) were measured. The results are shown in Table-2. Each characteristic was measured by the following measuring method. 1) Melt viscosity The urethane resin is heated to 100 ° C. and the BH type viscometer (N
O. Measured using 6 rotors (poise / 10)
0 ° C).

2) Softening point Urethane resin was heated and melted at 100 ° C. and measured by a ball and ring method (using silicone oil).

3) Open time Urethane resin melted at 100 ° C. is applied on plywood to a thickness of 100 μm, aluminum foil (0.1 mm thickness) is applied, and then the bonding adhesive is applied to the aluminum foil at regular intervals. The longest time to show wetness was defined as open time.

4) Initial Adhesion A (Creep Test) Urethane resin melted at 100 ° C. was applied on a steel plate at a thickness of 100 μm at 25 ° C. and immediately aluminum foil (0.1 m
(thickness m) was pressed by a rubber roll with a width of 1 inch at 180 degrees, and a static load of 300 g was applied at a temperature of 40 ° C. to observe the peeled state (peeling distance: 10 cm).

Evaluation Criteria No Peeling ・ ・ ・ ・ ・ ・ ・ ・ ◎ Peeling 5 cm or less ・ ・ ・ ○ Peeling 5-10 cm (Does not fall) ・ ・ ・ △ Drops ・・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ × 5) Initial adhesiveness B (180 degree peeling test) Urethane resin melted at 100 ° C is applied to a steel plate with a thickness of 100 microns and aluminum foil is immediately applied. The 180 ° peel strength was measured after 3 minutes from pressing open time with a rubber roll (unit: kg / inch). Comparative Example 1 50 parts of diol (A-1) and 50 of diol (B-1)
A urethane resin (P-2) was obtained in the same manner as in Example 1 except that 100 parts of the diol (A-1) was used.

The properties and adhesive properties of the urethane resin (P-2) were measured. The results are shown in Table-2. Comparative Example 2 50 parts of diol (A-1) and 50 of diol (B-1)
A urethane resin (P-3) was obtained in the same manner as in Example 1 except that 100 parts of the diol (B-1) was used.

The properties and adhesive properties of the urethane resin (P-3) were measured. The results are shown in Table-2.

[0044]

[Table 2]

Examples 2 to 4 A urethane resin (P- was prepared in the same manner as in Example 1 except that the combination of diol and diisocyanate shown in Table 2 was used.
4), (P-5) and (P-6) were obtained.

The properties and adhesive properties of the urethane resins (P-4) to (P-6) were measured. The results are shown in Table-3.

[0047]

[Table 3]

Example 5 A reflux circuit was set and air was previously replaced with nitrogen gas.
Diol (A-1) 775 was added to a 4-liter 4-necked flask.
After adding 50 parts of dibutyltin dilaurate and heating to 80 ° C. to uniformly dissolve the mixture, 80 ° C.
Then, 143 parts of 143 L of isonate was added dropwise, and the reaction was carried out at the same temperature until the isocyanate content became constant to obtain a prepolymer (A-1).

On the other hand, another diol (B-
2) 963 parts and 37 parts of 143 L of isonates were reacted to obtain a prepolymer (B-2).

50 parts of the prepolymer (A-1) and 50 parts of the prepolymer (B-2) were charged into a 2-liter 4-necked flask whose air was previously replaced with nitrogen gas, and the mixture was uniformly heated to 100 ° C.
After mixing in, defoam under reduced pressure and take out at 100 ° C.
A prepolymer (P-7) was obtained.

Properties of the resulting prepolymer (P-7),
The adhesive properties were measured. The results are shown in Table-4. Example 6 3 parts of 963 parts of diol (B-2) and 143 L of isonate
7 parts were reacted in the same manner as in Example 1 to give a prepolymer.
(B-2) was obtained.

On the other hand, 775 parts of diol (C-1) and 225 parts of 143 L of isonate were reacted in the same manner as in Example 1 to obtain prepolymer (C-1). 40 parts of prepolymer (A-1), 40 parts of prepolymer (B-2), and 20 parts of prepolymer (C-1) were mixed in the same manner as in Example 5, and degassed under reduced pressure to obtain prepolymer. (P-8) was obtained.

Properties of the resulting prepolymer (P-8),
The adhesive properties were measured. The results are shown in Table-4.

[0054]

[Table 4]

It can be seen from all the tables that the adhesive of the present invention has excellent initial adhesiveness.

[0056]

Since the adhesive of the present invention has both a crystalline aliphatic skeleton and an aromatic skeleton, it is possible to obtain a high degree of initial adhesive force between adherends, which cannot be obtained by these adhesives alone. Has a remarkable effect. In addition, the adhesive strength is excellent in a tacky state especially when the open time is extended.

Claims (8)

[Claims] 1. A hot type comprising a urethane resin containing isocyanate groups at both ends, which is obtained by reacting a polyol mixture of a crystalline aliphatic polyester diol (A) and an aromatic polyester diol (B) with a diisocyanate (C). Melt adhesive. 2. The adhesive according to claim 1, wherein the aromatic polyester diol (B) has a molecular weight of 5,000 to 40,000. 3. The adhesive according to claim 1, wherein the polyol mixture further contains an amorphous diol. 4. The polyol mixture comprises a crystalline aliphatic polyester diol (A), an aromatic polyester diol (B), and a non-crystalline diol, and the aromatic polyester diol (B) has a molecular weight of 5,000
The adhesive according to claim 1, which is -40,000. 5. A urethane resin containing isocyanate groups at both ends, which is obtained by reacting a crystalline aliphatic polyester diol (A) with a diisocyanate (C), and an aromatic polyester diol (B) with a diisocyanate (C). A hot melt adhesive containing a urethane resin containing isocyanate groups at both ends. 6. The molecular weight of the urethane resin containing isocyanate groups at both ends, which is obtained by reacting the aromatic polyester diol (B) and the diisocyanate (C), is 5,000 to 400.
The adhesive according to claim 5, which is 00. 7. The adhesive according to claim 5, further comprising a urethane resin containing isocyanate groups at both ends, which is obtained by reacting an amorphous diol with a diisocyanate (C). 8. A molecular weight 5,000 to 400 of a urethane resin containing isocyanate groups at both ends, which is obtained by reacting an aromatic polyester diol (B) with a diisocyanate (C).
The adhesive according to claim 5, further comprising a urethane resin having an isocyanate group of both ends, which is 00 and is obtained by reacting an amorphous diol with a diisocyanate (C).