JPS61183372A - Adhesive composition - Google Patents

Abstract

PURPOSE:To obtain a hot-melt adhesive retaining a high bond strength and having excellent high-temperature adhesion, by blending a thernoplastic copolyester elastomer with an ethylene/vinyl acetate copolymer. CONSTITUTION:An adhesive compsn consists of 15-80wt% thermoplastic copolyester elastomer (A) and 85-20wt% ethylene/vinyl acetate copolymer (B) having a vinyl acetate content of 10-50wt%. The elastomer (A) is a copolymer having an intrinsic viscosity of 0.5-1.5 wherein acid component consists of 50-95mol 5 of an arom. dicarboxylic acid or an ester forming derivative thereof (I), 5-50mol% of a dimer acid or an ester forming derivative thereof (II) and 0-30mol% of an aliph. dicarboxylic acid or ester forming derivarive thereof (III) other than dimer acid, glycol component consists of 60-97mol% of a 2-10C alkylene glycol (IV) and 3-40mol% of an aliph. long-chain glycol (V) and the sum of components (II) and (V) is 10-70mol%.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a hot melt adhesive composition that has high adhesive strength and excellent heat-resistant adhesive properties, and more particularly relates to a hot melt adhesive composition that has high adhesive strength and excellent heat-resistant adhesive properties. The present invention relates to a hot melt adhesive composition comprising a resin and an ethylene-vinyl acetate copolymer in a specific ratio.

(Prior art) (Problems to be solved by the invention) Hot melt adhesives are solvent-free and have 1:1 adhesive properties.

Due to its economic efficiency and convenience, such as adhesion to a relatively wide range of adherends, it has recently come to be used in large quantities in place of conventional solution-type adhesives and emulsion-type adhesives.

Among them, the most widely used is ethylene-
This is a vinyl acetate copolymer hot melt adhesive. Ethylene-vinyl acetate copolymers are used in combination with tackifiers, plasticizers, etc.

This product had poor heat-resistant adhesive properties and its adhesive strength was not at a sufficiently high level, so it could not be used in fields that required high performance adhesiveness, such as product assembly.

In order to improve these drawbacks, attempts have been made to blend polyester resins with ethylene-vinyl acetate copolymers. For example, JP-A-49-37941 attempts to improve adhesiveness by blending polyethylene isophthalate or polyethylene isophthalate terephthalate with an ethylene-vinyl acetate copolymer. Furthermore, JP-A-51-115541 discloses that a block copolyether ester copolymerized with poly(tetramethylene oxide) glycol as a soft segment is blended with an ethylene-vinyl acetate copolymer to improve adhesion to metals. is being attempted.

However, these polyester resins are essentially not compatible with the ethylene-vinyl acetate copolymer.

Since it is blended in a phase-separated state, it has not been possible to achieve the expected improvement in adhesive strength and heat-resistant adhesion, and it has not been put into practical use.

(Means for Solving the Problems) The present inventors have discovered that a specific copolyester containing a dimer acid or its hydrogenated product and an aliphatic long chain glycol has excellent compatibility with an ethylene-vinyl acetate copolymer. Adhesive compositions containing these compounds can eliminate the above-mentioned drawbacks and become hot-melt adhesives that have high adhesive strength, excellent heat-resistant adhesive strength, and excellent weather resistance. Heading.

This has led to the present invention.

That is, the present invention comprises (A) 50 to 95 mol% of aromatic dicarboxylic acid or its ester-forming derivative (1), 5 to 40 mol% of dimer acid or its hydrogenated product or its ester-forming derivative (II), and Aliphatic dicarboxylic acids other than dimer acids or their ester-forming derivatives CI [
[) 0 to 30 mol% as acid component, 60 to 97 mol% of alkylene glycol (IV) having 2 to 10 carbon atoms, and aliphatic long chain glycol (V) having an average molecular weight of about 350 to 6000.
) 3 to 40 mol % is a glycol component, the sum of the component (n) and (V) is 10 to 70 mol %, and the intrinsic viscosity [phenol:tetrachloroethane=1=1 (
Measured at 20°C in a mixed solvent with a weight ratio of 0.5 to 1.
5 thermoplastic copolymerized polyester elastomer 15-8
(B) an ethylene-vinyl acetate copolymer having a vinyl acetate content of 10 to 50% by weight and 85 to 20% by weight.

The thermoplastic copolymerized polyester elastomer of the present invention has a hard segment made of an aromatic dicarboxylic acid component and a soft segment made of a dimer acid and an aliphatic long chain glycol component in the form of a block. The aromatic dicarboxylic acid component constituting the hard segment contributes to raising the softening point of the thermoplastic copolymerized polyester elastomer and imparting heat-resistant adhesive properties, and its amount is 50 to 95 mol%, preferably 60% by mole based on the acid component. ~90
The range is mole %. When the proportion of the aromatic dicarboxylic acid component is less than 50 mol%, heat-resistant adhesive properties are obtained.

The cohesive force becomes low, while above 95 mol%.

That is, when the proportion of the dimer acid component is less than 5%, the effectiveness of the soft segment decreases, and flexibility is lost at low temperatures. Other aliphatic dicarboxylic acid components are appropriately used within the range of 0 to 30 mol % for the purpose of adjusting the softening point and melt viscosity of the resin. The dimer acid and aliphatic long chain glycol components that make up the soft segment increase the compatibility with the ethylene-vinyl acetate copolymer and lower the glass transition point.

Contributes to maintaining flexibility at low temperatures, the amount of dimer acid is 5 to 40 mol% of the total acid component, and the aliphatic long chain glycol component is 3 to 40 mol% of the total glycol component,
And the sum of the amounts of both components is 10 to 70 mol%. If the sum of both components exceeds 70 mol%, heat-resistant adhesion and cohesive strength will decrease, while if it is less than 10 mol%, not only will the compatibility with the ethylene-vinyl acetate copolymer deteriorate, but also the low-temperature properties will deteriorate. , the thermoplastic copolymer polyester elastomer becomes hard (and brittle). Thus, the presence of both dimer acid and long chain glycol is essential for the soft segment, and when dimer acid is used alone, ethylene-vinyl acetate It has poor compatibility with the copolymer, and furthermore, dimer acid itself has a relatively low molecular weight, and furthermore, it has good compatibility with the hard segment part, so the low temperature properties are insufficient because the two mix together, and the aliphatic long chain Conversely, when glycol is used alone, it has poor compatibility with aromatic dicarboxylic acids, resulting in poor heat-resistant adhesion and cohesive strength.

Furthermore, the melt viscosity also increases. That is, the soft segment composed of aliphatic long chain glycol in the thermoplastic copolymer polyester elastomer becomes compatible with the ethylene-vinyl acetate copolymer, improving the blending state of both resins, and creating a polyester elastomer with aromatic polyester segments as the main component. Since the hard segments that constitute the resin are not compatible with the ethylene-vinyl acetate copolymer, the softening point of the resin is suppressed, and the 9-carbon blend resin composition is expected to have excellent adhesive strength and high heat-resistant adhesive strength. .

Examples of aromatic dicarboxylic acids which are constituents of the thermoplastic copolymerized polyester elastomer of the present invention include terephthalic acid and isophthalic acid.

Examples include phthalic acid and naphthalene dicarboxylic acid, and one or more of these can be used, but terephthalic acid or a mixture of terephthalic acid and isophthalic acid is particularly preferably used. Dimer acid is a dimer of unsaturated fatty acids having 10 or more carbon atoms, and a preferred specific example is a dimer of linoleic acid. Hmpol 104
(manufactured by Emery Company, USA). Furthermore, Empol 1, which hydrogenated the double bond in the linoleic acid dimer,
010 (manufactured by Emery, USA) can also be preferably used.

Examples of aliphatic dicarboxylic acids other than dimer acid include one or more saturated aliphatic dicarboxylic acids having a methylene group of 4 to 20 carbon atoms, such as succinic acid, adipic acid, azelaic acid, sebacic acid, and dodecanedioic acid. Can be used.

As the alkyl glycol, those having 2 to 10 carbon atoms are used, such as ethylene glycol, trimethylene glycol, 1,4-butanediol, 5-bentanediol, 1,6-hexanediol, neopentyl glycol. One or more of these are preferably used. As a component of aliphatic long chain glycol, approximately 350
~6000. Preferably about 600-4000. For example, polybutadiene glycol having an average molecular weight of 1.2
-Polybutadiene glycol, 1,4-polybutadiene glycol, copolymers or mixtures thereof, and hydrogenated products thereof, polyisoprene glycol and hydrogenated products thereof, polyolefin glycols, and the like are preferably used. When commonly used poly(alkylene oxide) glycols, such as polyethylene glycol and polytetramethylene glycol, are used as the long-chain glycol component, they have poor compatibility with ethylene-vinyl acetate copolymers, resulting in poor compatibility with ethylene-vinyl acetate copolymers. It is not possible to obtain an adhesive composition having thermal stability and weather resistance, and the adhesive strength is also poor.

The thermoplastic copolymerized polyester elastomer in the present invention has an intrinsic viscosity in the range of 0.5 to 1.5.

If the intrinsic viscosity is less than 0.5, the cohesive force tends to decrease, while if it exceeds 1.5, the melt viscosity becomes too high, making it unsuitable for use.

The method for producing the thermoplastic copolymerized polyester elastomer in the present invention is not particularly limited, and can be carried out in accordance with known ordinary methods. For example, the aromatic dicarboxylic acid component, the dimer acid component, another aliphatic dicarboxylic acid component, the alkylene glycol component, and the long chain glycol component are directly esterified simultaneously or stepwise, or are transesterified and then polymerized. method can be adopted. Alternatively, a high molecular weight or low molecular weight copolymer polyester, a dimer acid or its hydrogenated product, and the long chain glycol component are transesterified,
In some cases, it is then polymerized.

It is also possible to adopt a method of doing this. Any known catalysts, stabilizers, modifiers or additives may be used during these polymerization or transesterification reactions.

The ethylene-vinyl acetate copolymer in the present invention has a vinyl acetate content of 10 to 50% by weight. If the vinyl acetate content is less than 10% by weight, adhesiveness will deteriorate and flexibility will be lost. Moreover, if it exceeds 50% by weight, the adhesive becomes too soft, which is not preferable. The ethylene-vinyl acetate copolymer may be partially saponified.

The blending ratio of (A) thermoplastic copolymerized polyester elastomer and (B) ethylene-vinyl acetate copolymer in the adhesive composition of the present invention is preferably in the range of 15/85 to 80/20 (weight ratio). is 20/80~60/4
It is in the range of 0. When the blending ratio of component (A) is less than 15% by weight, no improvement in heat-resistant adhesion is observed;
If it exceeds 80% by weight, the adhesive strength will deteriorate.

The adhesive compositions of the present invention typically include 2 tackifier resins that are incorporated into the ethylene-vinyl acetate copolymer.

Plasticizers, stabilizers, inorganic fillers, etc. can be included as necessary. In particular, tackifier resins have poor compatibility with conventional polyester resins.

A composition consisting of an ethylene-vinyl acetate copolymer, a tackifier resin, and a polyester resin had poor dispersibility and could not provide sufficient adhesive strength and heat-resistant adhesive properties. The polyester elastomer has excellent compatibility with the tackifier resin, and the dispersion state of the composition is very good.

Provides excellent adhesion.

The method for blending the thermoplastic copolyester elastomer and the ethylene-vinyl acetate copolymer for producing the adhesive composition of the present invention is preferably a melt blending method, for which a conventional roll, Nigoo, or Banbury mixer is used.
Kneading equipment such as single-screw and twin-screw extruders can be used.

The adhesive composition of the present invention can be applied in a molten state onto an adherend using a general real-melt applicator or roll coater, and can also be used in the form of, for example, powder, chip, tape, or string.

It is also possible to form the adhesive into various forms such as a film or a wave, and then to fuse the adherend by placing scissors 9 on the adherend and then heating it at a temperature above the softening point of the adhesive. Furthermore, it can be applied to a substrate as a coating agent and used to improve the surface of the substrate.

It can also be used as a hot-melt adhesive that is dissolved in a solvent, applied to a substrate, dried, and then bonded by reheat activation.

(Example) The present invention will be explained in more detail below with reference to Examples.

Note that "parts" in one example mean "parts by weight."

Further, the characteristic values in the two examples were measured by the following method.

(1) Softening point ("C) It was measured by the ring and ball method according to JIS JAI-7.

(2) Shear creep softening temperature ("C) 2.5cm X
A load of 300 g was applied in the shear direction to a test piece (kraft paper/kraft paper) bonded with an adhesive area of 2.5 cm, and the temperature was raised to 2° C. for 15 minutes.

The temperature was measured when the weight fell.

(3) Melt viscosity (cps) Measured at a temperature of 200°C using a Prusokfield Thermosel System HBTD type (manufactured by Brookfield Engineering Laboratories, Inc., USA).

(4) Peel adhesion strength (kg/25mm) JIS K -
6854, the peel adhesive strength at room temperature (20°C) was measured at a peel rate of 50 mm/min.

The bonding conditions are as follows.

(al adherend Ni-aluminum plate (2mm thickness)/aluminum plate (0,
1 mm thick) (BL bonding: The adhesive was heated and melted at 200° C. using a hot melt applicator, and applied to the adherend to a width of 25 mm and a lamp length of 50 mm, and bonded under pressure.

(5) Weatherability Using a sunshine weather meter, the tensile strength retention of the composition after 500 hours of irradiation was evaluated.

Examples 1-5. Comparative Examples 1-2 80 mol of dimethyl terephthalate, 20 mol of dimethyl isophthalate, dimer acid (manufactured by Emery, USA, Empo
l 1010) 0.01 mol of tetra-n-butyl titanate in 30 mol and 200 mol of 1,4-butanediol
mol was added as a catalyst and heated at 200° C. for 1 hour under a nitrogen atmosphere to perform a transesterification reaction.

Next, hydrogenated liquid polybutadiene glycol having a molecular weight of about 1000 (manufactured by Nippon Soda Co., Ltd., Gl-1000) 1
5 mol and 0.02 mol of tetra-n-butyl titanate were added and polycondensed by heating at 240°C under vacuum for 4 hours to form copolymerized polyester elastomer [1] (intrinsic viscosity 0.7
5, Softening point 165℃, Melt viscosity 260.000 cp
s) was created.

This copolymerized polyester elastomer [) and ethylene vinyl acetate copolymer [Mitsui Polychemical Co., Ltd.] EVAFL
EX' EV-220, vinyl acetate-containing ii 28% by weight Ml 150) were mixed in the proportions shown in Table 1, and 20
An adhesive composition was prepared by extrusion from a squirrel extruder with a 30 mmΦ screw heated to 0°C.

The obtained adhesive composition showed a good mixing condition and a softening point,
Table 1 shows the results of measuring the shear leap softening temperature, peel adhesion strength to an aluminum plate, and weather resistance.

Table 1 Comparative Example 3 0.01 mole of tetra-n-butyl titanate was added as a catalyst to 70 moles of dimethyl terephthalate, 30 moles of dimethyl isophthalate, and 160 moles of 1,4-butanediol, and 1 mole of tetra-n-butyl titanate was added as a catalyst at 200°C under a nitrogen atmosphere. The mixture was heated for a period of time to carry out a transesterification reaction.

Next, 30 mol of polytetramethylene glycol (manufactured by Mitsubishi Kasei Corporation, PTMG-1000) having a molecular weight of about 1000 and 0.02 mol of tetra-n-butyl titanate were added.

Polycondensation was performed by heating at 240°C for 4 hours under vacuum to form a copolymer polyester elastomer [■] (intrinsic viscosity 0.83
．． Softening point 158℃, melt viscosity 530.000 C05)
It was created.

40 parts of this copolymerized polyester elastomer (1) and ethylene-vinyl acetate copolymer (EVAFLEX"EV
-220, manufactured by Mitsui Polychemical Co., Ltd.) 60 parts at 200°C
An adhesive composition was prepared by extrusion from a twin-screw extruder with a 30IIIφ screw heated to .

The dispersion state of this adhesive composition is not very good.

The softening point is 128°C, and the shear creep softening point is 83°C.

Peel adhesion strength to aluminum plate 1.8kg/25
The weather resistance deteriorated severely after 200 hours of irradiation, and the shape became crumbly and the 2 strength retention rate was 0%.

By the way, the weather resistance of this copolymerized polyester (If) alone was 0% in strength retention after 100 hours of irradiation Example 6: 60 mol of dimethyl terephthalate, 2 mol of dimethyl adipate
0 mol, dia-acid (Empo110 manufactured by Emery, USA)
10) 20 moles and 1,4-butanediol 124.5
0.01 mol of tetra-n-butyl titanate was added as a catalyst to the mol, and the mixture was heated at 200° C. for 1 hour in a nitrogen atmosphere to perform a transesterification reaction. Next, one molecular weight is about 1000
10 moles of hydrogenated liquid polybutadiene glycol (manufactured by Nippon Soda Co., Ltd., G1-1000) and 0.02 moles of tetra-n-butyl titanate were added, and
Polycondensation was carried out by heating for a period of time to produce a copolymerized polyester elastomer [■] (intrinsic viscosity: 0.75°, softening point: 175°C, melt viscosity: 410.000 cps).

This copolymer polyester elastomer CII [)30
and ethylene-vinyl acetate copolymer [EVAFLEX”
EV-410, manufactured by Mitsui Polychemical Company.

Vinyl acetate content 1i19% by weight, MI400) 40
Esterified product of hydrogenated rosin and hydrogenated rosin (manufactured by Vercules, USA).

Foral 85) 15 parts and terpene phenol resin (YS-Polyster, T-115, manufactured by Yasuyu Kogyo Co., Ltd.)
2 of 30mmΦ screw heated 15 parts to 190℃
An adhesive composition was prepared by extrusion from a screw extruder.

This adhesive composition exhibits good dispersion and has a softening point of 12
1°C, a shear leap softening point of 09°C, and a peel adhesive strength against an aluminum plate of 4.5 kg/25 mm.

(Effects of the Invention) The adhesive composition of the present invention has better adhesive strength than conventionally known ethylene-vinyl acetate-based real-melt adhesives or real-melt adhesives made of ethylene-vinyl acetate copolymer and polyester resin. Excellent heat-resistant adhesion, metal,
Preferably used for adhering wood, paper, plastics, fibers, etc. Furthermore, the adhesive composition of the present invention also has the feature of excellent weather resistance.

Claims (1)

[Claims] (1) (A) Aromatic dicarboxylic acid or its ester-forming derivative (I) 50 to 95 mol%, dimer acid or its hydrogenated product or its ester-forming derivative (II)
5 to 40 mol% and 0 to 30 mol% of an aliphatic dicarboxylic acid or its ester-forming derivative (III) other than dimer acid as acid components, and 60 to 97 mol% of alkylene glycol (IV) having 2 to 10 carbon atoms; Average molecular weight approximately 350-60
00 aliphatic long chain glycol (V) as the glycol component, the sum of the components (II) and (V) is 10 to 70 mol%, and the intrinsic viscosity [phenol:tetrachloroethane = 20 in a mixed solvent of 1:1 (weight ratio)
15 to 80% by weight of a thermoplastic copolymerized polyester elastomer having a temperature of 0.5 to 1.5 (measured at °C) and (B) 85 to 20% by weight of an ethylene-vinyl acetate copolymer having a vinyl acetate content of 10 to 50% by weight. Adhesive composition consisting of %.