JPS5819711B2 - Setuchiyakuzaisoseibutsu - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hot melt adhesive having high adhesive strength and excellent heat resistance, solvent resistance and hot water resistance. The present invention relates to a hot-melt adhesive, particularly an adhesive composition for metals and fibers, comprising a resin blend composition of an ester and an ethylene-vinyl acetate copolymer.

Hot-melt adhesives made of 100% solids, which are applied in a hot molten state and then cooled below their melting point to bond between substrates, have the major characteristics of fast bonding time and the ability to cover a wide range of adhesives. Compared to conventional solution-type and emulsion-type adhesives, which are fluid and contain a solvent or dispersion medium and solidify by evaporating the solvent at room temperature or by heating, the bonding time is long, whereas the solidification time of the base polymer is long. This has the advantage of requiring only a single layer, and therefore the curing time is short.

Furthermore, since no solvent or dispersion is required, the amount of heat required for evaporation and drying equipment are no longer required, and the method is showing great growth in the direction of labor saving, energy saving, and resource saving.

Advantages of introducing a hot melt system into the bonding process include improved productivity, reduced labor costs, and improved bonding reliability.

However, the most widely used hot melt adhesives are ethylene-vinyl acetate copolymer hot melt adhesives, which are often used as a ternary formulation of ethylene-vinyl acetate copolymer/rosin/wax. , poor heat resistance, poor solvent resistance, poor hot water resistance, and lack of adhesive strength at a sufficiently high level, so that it cannot be used for certain adhesive applications.

The present invention is particularly applicable to hot melt adhesive applications that require high adhesive strength, excellent performance in heat resistance, solvent resistance, and hot water resistance, such as metal adhesion (or coating) for food cans, and fiber adhesion. The purpose is to provide hot melt adhesives suitable for various uses.

Polyesters whose main components are polybutylene ethylene terephthalate/polybutylene isophthalate copolyesters are more easily coated and bonded by thermal adhesion than other polyesters, such as polyesters whose main components are polyethylene terephthalate/polyethylene isophthalate. It possesses many excellent properties.

In other words, it easily crystallizes even at low temperatures and exhibits high adhesive strength immediately after bonding to metal.

Furthermore, when the obtained coated metal material is molded and used, the degree of post-crystallization is relatively small even if heat treatment is performed, for example.
It has high stability in terms of adhesive strength and appearance.

However, when a resin and metal laminate obtained using polyester whose main component is polybutylene lentileffrate/polybutylene isophthalate is subjected to steam treatment, the resin and metal surfaces may peel off or the coating may be easily damaged. For example, when a metal container such as a can is formed using this coated metal plate and subjected to steam treatment, the coating peels off and the contents come into direct contact with the metal surface, causing deterioration of the contents due to rusting, corrosion, etc. There may be consequences.

The reason for this peeling between resin and metal during steaming treatment is not only that the initial adhesive strength level is low, but also that the resin undergoes structural changes such as crystallization due to the influence of water and/or heat during steaming treatment, resulting in the delamination at the adhesive interface. It is presumed that stress and strain occur, resulting in peeling.

Therefore, the present inventors have already developed a resin blend in which an ethylene-vinyl acetate copolymer is melt-blended in a certain composition to an epoxyester mainly composed of polybutylene terephthalate/polybutylene isophthalate. It has been found that the concentration of stress and strain mentioned above is alleviated and that the material does not peel off even when subjected to steaming treatment.

However, such resin compounds do not have sufficient adhesion to metals, and may even peel off if the steam treatment conditions are severe (high temperature, long time), so improvements are desired. was.

The present inventors have improved the above-mentioned drawbacks when coating metal with a blended composition of polybutylene terephthalate/polybutylene isophthalate copolyester and ethylene-vinyl acetate copolymer, and improved adhesive strength and hot water resistance. As a result of intensive research to obtain superior hot melt adhesives (and coatings), we developed polybutylene lentil reflex crate/
A resin formulation in which block copolyether ester, which is a block copolymerization of polybutylene isophthalate and poly(alkylene oxide) glycol whose main component is poly(tetramethylene oxide) glycol, is blended with a certain composition of ethylene-vinyl acetate copolymer. The inventors have now discovered that by thermally adhering the composition to a metal surface, a metal coating can be obtained that is significantly improved from the above-mentioned drawbacks, and the present invention has been achieved.

That is, the present invention is a polyester copolymer whose main carboxylic acid component is terephthalic acid or a mixture of terephthalic acid and isophthalic acid in which the terephthalic acid is 45 or more, and whose diol components are a low-molecular diol and a high-molecular diol, A hard segment is a polyester segment containing a diol component in which 50 moles or more of the low molecular diol component is 4-butanediol; Glycol number average molecular weight 400-4
,000 poly(alkylene oxide) glycol component as a soft segment, and the block copolyether ester (A ) 90 to 30% by weight, and an ethylene-vinyl acetate copolymer (B110 to 70% by weight) having a vinyl acetate component content of 1 to 50% by weight, in which acetic acid Vinyl content is 2-25
The present invention provides a hot melt adhesive composition comprising a resin compounded composition having a weight ratio of most often.

The dicarboxylic acid component used in the block copolyether ester (A) of the present invention is terephthalic acid or a mixture of terephthalic acid and isophthalic acid containing 45 mol% or more of terephthalic acid, and the dicarboxylic acid component is terephthalic acid with a content of 45 mol% or more.
Terephthalic acid should account for 5 mol %, more preferably 990 to 50 mol %.

Isophthalic acid is preferable as the dicarboxylic acid component capable of modification with terephthalic acid, and particularly when used in a ratio of terephthalic acid/isophthalic acid -90 to 50/10 to 50 (mol), favorable results are obtained.

If the terephthalic acid component is less than 45 mol %, the resin's adhesive strength at high temperatures, hot water resistance, and film strength are significantly reduced.

Further, the reasons why isophthalic acid is preferable as a dicarboxylic acid component copolymerizable with terephthalic acid are its hot water resistance, crystallization properties, and adhesive strength.

The remaining dicarboxylic acid components of terephthalic acid and isophthalic acid that can be used in the present invention include azelaic acid, sebacic acid, adipic acid, dodecanedioic acid, etc. having 2 to 2 carbon atoms.
Examples include aliphatic dicarboxylic acids such as phthalic acid, aromatic dicarboxylic acids such as naphthalene dicarboxylic acid, and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, and the amount that can be copolymerized is approximately 30 moles of the total dicarboxylic acid components. %
He is talented.

The low molecular weight diol that forms the short chain polyester segment in the block copolyether ester has excellent melt clay properties, and in particular improves the crystallinity of the block copolyester to provide a resin with excellent moldability, adhesion and hot water resistance. , 4-butanediol is preferred, with 50 mol% of the low molecular weight diol and 70 mol% or more of the low molecular weight diol being 1,
It needs to be 4-butanediol.

The remaining low molecular weight diols of 1゜4-butanediol that can be used include aliphatic diols having 2 to 10 carbon atoms, namely ethylene glycol, propylene glycol, neopentyl glycol, 1,5-bentanediol,
-hexanediol, and alicyclic diols such as 1,4-cyclohexane dimetatool and 1,4-cyclohexanediol, either singly or in mixtures.

More than 50% by weight of the poly(alkylene oxide) glycol that reacts with the dicarboxylic acid component to form a long-chain polyether ester soft segment is poly(tetramethylene oxide) glycol, which has heat resistance, water resistance, and chemical resistance. From the viewpoint of properties, poly(tetramethylene oxide) glycol is preferred.

The remaining poly(alkylene oxide) glycol is poly(1,2- and 1°3-propylene oxide).
Examples include glycol, a copolymer of ethylene oxide and propylene oxide, and polyethylene glycol.

The average molecular weight of poly(alkylene oxide) glycol is 400 to 4.0001, preferably 500 to 3.00.
It is 0.

Poly(alkylene oxide) with molecular weight in this range
The block copolyether ester produced from glycol forms microphase-separated regions, exhibits good rubber elasticity, and exhibits excellent adhesion even during steam treatment.

In the block copolyether ester, the proportion of the soft segment mainly composed of poly(tetramethylene oxide) glycol is most often 5 to 80% by weight, and if it is less than 5%, it has an effect of improving hot water resistance and adhesiveness. It is not noticeable, and if it exceeds 80%, the strength of the resin coating will decrease significantly.

Block copolyether ester includes polycarboxylic acid,
Polyfunctional components such as polyols and polyoxycarboxylic acids may be included, such as trimellitic acid, pyromellitic acid, trimesic acid, and 3,3'.

4.4'-benzophenonetetracarboxylic acid, ■.

2.3. Specific examples include tri- and tetracarboxylic acids such as 4-butanetetracarboxylic acid and nadic acid, and derivatives such as acid anhydrides and acid esters thereof, and polyols such as glycerin, pentaerythritol, and trimethylolpropane. .

The method for producing such block copolyether ester particles is arbitrary, but the degree of polymerization is not particularly limited as long as the intrinsic viscosity (25°C) measured in orthochlorophenol is 0.5 or more.

The ethylene-vinyl acetate copolymer (B), which is the other component forming the resin composition in the present invention, has a vinyl acetate content of 10 to 50% by weight.

The lower limit of the vinyl acetate content is primarily determined by adhesiveness and flexibility, and the upper limit is determined by the tackiness of the adhesive.

The ethylene-vinyl acetate copolymer may be partially saponified, with the degree of saponification ranging from 0 to 75%.

As the degree of saponification is increased, the crystallinity of the ethylene-vinyl acetate copolymer is improved, the softening temperature (heat resistance) and melt viscosity are increased, and the hot water resistance and solvent resistance are also improved accordingly.

However, the degree of saponification must not exceed 75% because the adhesiveness decreases rapidly if the degree of saponification exceeds 75%.

As the ethylene-vinyl acetate copolymer, a modified graft copolymer obtained by grafting about 0.5 to 4% by weight of aliphatic carboxylic acid may be used.

The important point of the present invention is such a block copolyether ester (8 and ethylene-vinyl acetate copolymer (B)).
A block copolyether ester and an ethylene-vinyl acetate copolymer are blended in a weight ratio of 90-30/10-70, and It is necessary that the vinyl acetate content of 2 to 25% by weight.

When the amount of block copolyether ester (5) is more than 90% by weight, peeling occurs during steaming treatment as described above, and hot water resistance becomes insufficient.

On the other hand, when the amount of the ethylene-vinyl acetate copolymer (B) exceeds 70% by weight, the heat resistance decreases and the strength of the adhesive layer resin film at high temperatures becomes insufficient.

Also, the vinyl acetate content in the total resin formulation is 2 to 25% by weight.
The reason for this is that there is a strong correlation between vinyl acetate content and adhesive strength, and high adhesive strength cannot be obtained if the vinyl acetate content is too high or too low.

The method for producing the ethylene-vinyl acetate copolymer is also arbitrary, but
Melt index (MI) is approximately 5 to 300 (g/
10m1n: Based on ASTM D-1238 revised)
That's fine.

The method of blending the block copolyether ester (support) and the ethylene-vinyl acetate copolymer (B) is preferably a melt blending method, using a common mixer such as a roll, a kneader, a panburi mixer, or a single-screw or twin-screw extruder. can be melt-blended.

Since the compatibility between the two is quite excellent, no special kneading equipment is required, and it is sufficient to mix them to the extent that the dispersed particle size is from several microns to several + microns.

Methods for coating and thermally bonding metal surfaces with a resin compound composition include, for example, a method in which the resin composition is formed into a film in advance and the film or metal is heated, or both are heated and thermally bonded; While forming the composition into a film, the film is directly applied to the surface of the metal plate while it is still in a semi-molten state and adhered. Alternatively, the powdered resin composition is applied to the metal plate by fluid dipping or electrostatic coating. Examples include a method of adhering it to a surface and then thermally bonding it, but there are no particular limitations as long as the method is thermal bonding.

In the present invention, the metal coated with the resin composition consisting of the Yangji block copolyether ester and the ethylene-vinyl acetate copolymer is an iron material, a steel material in any shape such as a plate, a line, or a block, or tin, zinc, or chromium. There are no particular restrictions on the material or shape of the metal, and if desired, an undercoat may be applied to the metal surface when coating it with a resin composition. It is also possible to laminate the resin after applying the resin.

The thus obtained coating has a resin coating that adheres to metal surfaces with even higher adhesion strength, and has excellent steam heat treatment resistance, and cans, trays, and other metal containers, electric wires, Interior and exterior materials for machines, furniture, buildings, ships, etc. have excellent durability and appearance under various conditions.

As described above, the composition of the present invention has high adhesive strength, excellent hot water resistance, and excellent solvent resistance and flexibility, so it can be used for adhesion of adherends other than metals that require such performance. It turns out that it can also be applied.

For example, in the field of clothing adhesion, hot melt adhesives are widely used in applications such as adhesive interlining, adhesive sewing, non-woven fabrics, binders, and patch/name bonding because they contribute to labor saving and speeding up. It is becoming.

However, in terms of fiber adhesion performance, it has high adhesive strength, softens and bonds at a relatively low temperature of about 100 to 160°C, has excellent dry cleaning resistance (solvent resistance), and excellent hot water washing resistance. These include the fact that there is no hardening of the texture of the bonded area, and at present there is no known hot melt adhesive that satisfies all of these required performances.

Copolymerized polyamides used for relatively high-grade adhesive applications also have the drawbacks of low adhesion to polyester synthetic fibers, poor hot water resistance, and hard texture at the bonded area.

Therefore, the resin composition shown in the present invention has the possibility of overcoming the above-mentioned drawbacks, and when the resin composition was used in the form of powder, film, or thread to bond various textiles, it was found that it exhibited excellent fiber adhesion performance. I found it.

In the resin formulation applied to such textile adhesives, the ratio of polybutylene terephthalate/polybutylene isophthalate copolyester corresponding to the bird segment of the block copolyether ester is about 70/30 to 45155 in relation to the softening temperature during bonding. It is particularly preferable that the range is within the range of , but other ranges that define the composition of the resin compound can be applied as they are.

Therefore, the resin composition of block copolyether ester and ethylene-vinyl acetate copolymer provided by the present invention can be used as a hot melt adhesive with excellent heat resistance, adhesion, hot water resistance, and solvent resistance. , it can be applied to the field of hot melt adhesives, which requires the above-mentioned performance.

Next, examples of the present invention will be shown, but the following examples are not intended to limit the present invention.

Example 1 75.7 parts of dimethyl terephthalate, 40.7 parts of dimethyl isophthalate, 97.2 parts of 1,4-butanediol, and 60.0 parts of poly(tetramethylene oxide) glycol (number average molecular weight about 1000). , and 0.085 part of titanium tetrabutoxide were heated at 210° C. for 2 hours, and the generated methanol was distilled out of the reaction system.

The reaction temperature was then raised to 250°C, the pressure within the system was increased to 0.2 mm Hg for 1 hour, and the polycondensation reaction was carried out at this pressure for 1 hour and 40 minutes, resulting in a viscous polymer liquid.

The intrinsic viscosity in orthochlorophenol (25°G) was 0.87 and the melting point was 152°C.

(B) As an ethylene-vinyl acetate copolymer, Mitsui Polychemical Co.'s 'EVAFLEX'' p-2807 (
MI-15) containing 28% vinyl acetate was prepared.

(C) to 1) The following four types of compositions were extruded from a 30 mmφ screw extruder heated to 2oo°C, pelletized, and dried.

The pellets (F') were press-molded into a film at 2000G to create a film with a thickness of 60μ.

These films were applied to a section of a steel plate (U, S, G = #30) preheated to 240-2600C at a rate of 2 kg/d.
A sample of a steel plate coated with a resin layer was obtained by pressing at a pressure of 5 seconds.

Using a tensilon meter, measure the above sample to JIS-68.
Peeling rate 20 cIrL/min according to the method of No. 54
Peel strength was measured under the following conditions.

Furthermore, each of the above samples was heat treated by immersing them in hot water at 98°C for 60 minutes, and after cooling, the peel strength was measured in the same manner as above.

The results of each measurement are shown in Table 1.

Example 2 A block copolyether ester was produced at the same polymerization ratio as in Example 1 except that the number average molecular weight of poly(tetramethylene oxide) glycol was changed from 1000 to 2000.

This was melt blended with the ethylene vinyl acetate copolymer of Example 1(B) in a weight ratio of 60/40 and pelletized (this sample is designated by symbol G).

) On the other hand, by ordinary ester polymerization method, the ratio of polybutylene terephthalate to polybutylene isophthalate is 65/
Polytetramethylene oxide glycol-free copolyester I of 35 was prepared and melt blended with ethylene-vinyl acetate copolymer (B) to form a blended composition (I).
pellets.

(The polymer chips of (■) to (I) were formed into a 45 μm thick film using a 45 crystal diameter extruder equipped with a film die, and thermally bonded to a steel plate in the same manner as in Example 1.

The coated sample was immersed in hot water at 98°C for 60 minutes and 300 minutes to determine the change in peel strength, and then placed in an autoclave for 1 hour.
A heat treatment was performed in hot water at 20° C. for 60 minutes to determine the change in peel strength.

These results are shown in Table 2, and the method (G) of the present invention using a copolyether ester obtained by block copolymerizing poly(tetramethylene oxide) glycol has better hot water resistance.

Example 3 A block copolymer having a copolyester with a polybutylene terephthalate/polybutylene isophthalate ratio of 70/30 as a hard segment and a poly(tetramethylene oxide) glycol having a number average molecular weight of about 1000 as a soft segment of 30% by weight. ether ester<
J) was produced.

For comparison, 1 block copolyether ester (0) was prepared in the same manner as shown in Table 3, except that the components of the block copolyether ester were changed.

The above block copolyether esters (J) to (0) were mixed with 'EVAFLEX'' p-1907 (ethylene vinyl acetate copolymer manufactured by Mitsui Polychemical Co., Ltd.; vinyl acetate content 19-fold mode, MI-15) and 70: They were melt-blended in a panburi mixer at a ratio of 30, formed into a film in the same manner as in Example 1, and then bonded to a steel plate and heated at 98°.
Changes in peel strength after 60 minutes in hot water of C were determined.

Example 4 Block copolyetherester (J) obtained in Example 3
EV with a vinyl acetate content of 33 parts per 100 parts by weight
AFLEX''p-3307 and vinyl acetate content is 55
5.50.80 parts by weight of Soaflex "BH" (ethylene-vinyl acetate copolymer manufactured by Nippon Gosei) were respectively melted and a film of the blended composition was placed on tin-free steel. It was coated in the same manner as 1.

The peel strength of each sample and the peel strength after being immersed in hot water at 98°C for 120 minutes were measured according to the method of JIS-6854.

The measurement results are shown in Table 4. Furthermore, the resin layer using a material with a high vinyl acetate content (Soaflex) has strong adhesiveness.
The film strength was also low.

Example 5 A block copolyether ester obtained by copolymerizing a 33 weight percent block copolymer of poly(tetramethylene oxide) glycol with a polybutylene terephthalate/polybutylene isotucrate ratio of 50,150 and a number average molecular weight of 2,000.
P) was produced in the same manner as in Example 1.

The melting point of this polymer was 120°C and the intrinsic viscosity in octochlorophenol was 1.10.

The block copolyether ester is melt-blended with an equal amount of Dumilan "D-219" (partially saponified ethylene-vinyl acetate copolymer) manufactured by Mitsui Polychemical Co., Ltd.
A 60μ film was formed by hot pressing at 200°C.

Sandwich the tape between two pieces of polyester/cotton broadcloth, 16
300g/Cr using a hot plate heated to 0°C. The adhesive was bonded by heat-pressing for 20 seconds at a pressure of L, and the peel strength of the bonded portion was measured.

Then, it was treated in warm water at 80° C. for 30 minutes, and separately immersed in Trichlorene for 30 minutes to measure changes in adhesive strength.

As a comparison, the same tests were carried out with films from 'Dumilan' D-219 and a copolymerized polyamide (Toshi Seisaku '832p').

Example 6 Block copolyetherester (A) obtained in Example 1
40 parts by weight, "ELVAX" 150 (DuPont's ethylene-vinyl acetate copolymer with a vinyl acetate content of 3 parts by weight)
A film prepared from the blended composition was examined for peel strength and hot water resistance in the same manner as in Example 1.

As a comparative example, ' Piccolastic //A50
(low molecular weight styrene homopolymer from Industria Abe Chemical Co., Pennsylvania) or "ELVAX"
Similar tests were conducted on resins containing both 150 and 'Piccolastic'' A50 in the ratios shown in Table 6.

These results are shown in Table 6.

Claims (1)

[Claims] 1 A polyester copolymer whose main carboxylic acid component is terephthalic acid or a mixture of terephthalic acid and isophthalic acid in which the molar ratio of terephthalic acid is 45 or more, and whose diol components are a low-molecular diol and a high-molecular diol, 50 mol% or more of the low molecular weight diol component is 1,4-
A polyester segment containing a diol component which is butanediol is referred to as a bird segment, and a poly(alkylene oxide) glycol having a number average molecular weight of 400 to 4.000, in which 50% by weight or more of the polymeric diol component is poly(tetramethylene oxide) glycol. The polyether ester segment containing the component is used as a soft segment,
and the soft segment is 5 per total weight of the copolymer.
~80% by weight copolymerized block copolyetherester 90% to 30% by weight and an ethylene-vinyl acetate copolymer (B) containing 1% to 50% by weight of vinyl acetate component
A hot melt adhesive composition comprising a resin blended composition containing 10 to 700 to 70% by weight of vinyl acetate, the composition containing 2 to 25% by weight of vinyl acetate.