JPS64414B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an adhesive resin composition with excellent durability obtained by melt-mixing a specific saponified ethylene-vinyl acetate copolymer and a monoolefin-unsaturated carboxylic acid anhydride copolymer. It is. In general, saponified ethylene-vinyl acetate copolymer has higher melting point, hardness, tensile bending strength, bending rigidity, etc., as well as solvent resistance and abrasion resistance, compared to its raw material resin, ethylene-vinyl acetate copolymer. , excellent gas permeability. Furthermore, it has excellent adhesion to various inorganic and organic substrates including metals, and is widely used as coating agents for powder paints, adhesives for textile interlining, and various lamination adhesives. For example, a method is known (Japanese Patent Publication No. 10529/1983) in which metals and the like are coated with powder of a specific saponified ethylene-vinyl acetate copolymer. However, when only the saponified copolymer is used as an adhesive, the initial adhesion to metals and many other base materials is good, but it has poor resistance to hot water, salt water, heat, cold, and other weather resistance. The so-called secondary adhesion under the usage environment is not sufficient, and improvement thereof is desired. The present inventors have conducted intensive studies to improve secondary adhesive properties such as hot water resistance and salt water resistance, and as a result, have discovered a new resin composition with strong adhesive properties, and have achieved the present invention. Ivy. That is, the present invention has a saponification rate of 50 to 50% obtained by saponifying an ethylene-vinyl acetate copolymer having a vinyl acetate content of 10 to 55% by weight and a melt index of 5 to 500.
100 parts by weight of the 100% saponified copolymer and the monoolefin and one or more unsaturated carboxylic anhydrides containing 5 to 50 mol% of the unsaturated carboxylic anhydride. Copolymer 0.01~2.5
The present invention provides an adhesive resin composition obtained by melt-mixing parts by weight. Here, the following may be considered as the reason why the resin composition of the present invention maintains excellent adhesive properties under various severe environmental conditions as described above. That is, saponified ethylene-vinyl acetate copolymers are generally obtained by saponifying ethylene-vinyl acetate copolymers in an organic solvent in the presence of an alkali such as sodium hydroxide. By-product sodium acetate, excessively added sodium hydroxide, etc. persistently remain in the saponified product, and it is very difficult to completely remove them by ordinary washing. Therefore, the resulting saponified product generally contains several hundred to several thousand ppm of sodium compounds. Since these compounds are highly water-soluble, under the environment in which they are generally used, they absorb moisture and these sodium compounds are eluted to the adhesive layer interface.
It is thought that these factors cause the adhesive strength to gradually decrease. Here, a polymer having a functional group that easily reacts with the sodium compound to form a stable salt, such as the monoolefin-maleic anhydride copolymer discovered in the present invention, is used. When it is added to a saponified ethylene-vinyl acetate copolymer and melt-kneaded, the residual sodium compound contained in the saponified product reacts with the maleic anhydride in the added copolymer, converting it into a maleate salt. For this reason, it is thought that the adhesive strength does not decrease under the above-mentioned usage environmental conditions and exhibits stable and strong adhesiveness. Note that such an effect is also observed when a monoolefin-unsaturated carboxylic acid copolymer, such as an ethylene-(meth)acrylic acid copolymer, is added, but when the monoolefin of the present invention is combined with maleic anhydride, etc. There is no significant effect like copolymers with acid anhydrides. Furthermore, an interesting feature discovered in the present invention is that, for example, the composition obtained by adding an ethylene-maleic anhydride alternating copolymer to the ethylene-vinyl acetate copolymer and melt-kneading it has melt fluidity. It means improving. This also has advantages such as improved workability. The saponified ethylene-vinyl acetate copolymer used in the present invention can be produced by a known method using an ethylene-vinyl acetate copolymer as a raw material. For example, homogeneous solution reactions in good solvents such as hydrocarbons such as toluene and xylene or mixed solvents in which alcohols such as methanol are added, or heterogeneous reactions in non-solvents using alcohols such as methanol and ethanol. Can be produced by reaction. As the saponification reaction catalyst, hydroxides of alkali metals such as sodium and potassium, and alkoxides such as methoxide are used. Further, the raw material ethylene-vinyl acetate copolymer is used in the form of powder or granules such as pellets, depending on the purpose of use. The vinyl acetate content of the ethylene-vinyl acetate copolymer is limited to 10 to 55% by weight. If the vinyl acetate content is less than 10% by weight, it is difficult to obtain a product with the above-mentioned performance as a saponified product, and if the content exceeds 55% by weight, processability tends to deteriorate, which is not preferable. .
The vinyl acetate content of the raw material copolymer is particularly 15
~50% by weight is preferred. Furthermore, as a raw resin, if necessary, a third comonomer copolymerizable with ethylene and vinyl acetate, such as unsaturated hydrocarbons such as propylene, butene-1, and styrene, or unsaturated hydrocarbons such as (meth)acrylic acid and its esters, may be added. Saturated carboxylic acids and their derivatives, etc.
It is also possible to use a copolymerized material of about 10% by weight or less. Further, the melt index of the ethylene-vinyl acetate copolymer used is in the range of 5 to 500. If the melt index is less than 5, the processability of the saponified product obtained will deteriorate, and if it exceeds 500, the strength of the resin will decrease, which is not preferred. The saponification rate of the saponified ethylene-vinyl acetate copolymer is in the range of 50 to 100%, preferably 80 to 100%, whereby a product having excellent adhesiveness and resin strength can be obtained. This saponified product generally contains an alkaline substance added in excess during the saponification reaction and acetate as a by-product. There is no particular limitation on the amount of these, but it is preferably 2% by weight or less, particularly 0.5% by weight or less in terms of the amount of alkali metal. Direct copolymers of monoolefin and one or more unsaturated carboxylic acid anhydrides which are added as a component of the adhesive composition of the present invention include, for example, ethylene, propylene, butene-1, isobutene-1, isobutene-1, 4- One or more monoolefins selected from methylpentene-1, hexene-1, heptene-1, octene-1, etc., and selected from maleic anhydride, itaconic anhydride, citraconic anhydride, hymic anhydride, etc. It is a direct copolymer with one or more unsaturated carboxylic acid anhydrides. The direct copolymer is a copolymer obtained by copolymerizing monomer components,
Graft copolymers are not included. Among these copolymers, monoolefin-maleic anhydride copolymers are preferred from the standpoint of both performance and economy. The content of unsaturated carboxylic acid anhydride in these copolymers is preferably in the range of 5 to 50 mol%, and alternating copolymers of ethylene or isobutylene and maleic anhydride are particularly preferably used. . Moreover, the molecular weight of the direct copolymer is 1000~
Preferably something in the 200000 range. These copolymers can be produced by known direct polymerization methods. Moreover, commercially available products that are easily available can also be used as they are. Further, the unsaturated carboxylic anhydride group in the monoolefin-unsaturated carboxylic anhydride copolymer may be partially ring-opened and esterified. The adhesive resin composition of the present invention has the above-mentioned ethylene-
For 100 parts by weight of saponified vinyl acetate copolymer,
It was produced by directly adding 0.01 to 2.5 parts by weight of the copolymer and melt-mixing. Here, it is important that the composition of the present invention is not a mere mixture of these two components, ie, a mixture of powder or granules, but is produced by melt-mixing them. This results in compositions with significantly improved durable adhesion. This composition can be easily produced by melt-kneading the saponified ethylene-vinyl acetate copolymer at a temperature from above the melting point to 200° C. using a screw extruder, kneader, Banbury mixer, or the like. On this occasion,
It is desirable that the volatile content such as solvent contained in the composition be reduced to 0.5% or less in view of problems such as foaming in subsequent processing steps. The composition thus obtained can be processed into various forms such as powder, pellets, fibers, and films depending on the purpose of use. In addition, in the melt-kneading process or the subsequent processing process, antioxidants, light stabilizers, heat stabilizers, colorants such as organic or inorganic pigments, crosslinking agents, and blowing agents may be added to the composition of the present invention as necessary. Various additives can be added, such as lubricants, surface smoothness or surface gloss improvers, plasticizers, and various organic or inorganic fillers. Furthermore, it can also be used by blending with various resins. The adhesive resin composition obtained by the present invention can be widely used as a coating material, a binder, a lamination adhesive, etc. for various base materials such as metals, polymeric materials, and inorganic materials. Among these base materials, it can be particularly effectively used as a coating agent for metals. In this case, powder coating methods are recommended. Metals, which are one of the base materials mentioned above, are listed in the circumferential table.
It is a single substance selected from the group consisting of B, -B, -B, and the group, or an alloy containing at least one component thereof. The preferred metal is aluminum;
iron, nickel, cobalt, chromium, zinc, tin,
titanium, gold, silver, copper, etc., and carbon steel,
These are surface-treated products made of various alloys such as stainless steel, brass, bronze, and duralumin, and iron such as galvanized iron and tinplate. In order to effectively carry out the present invention, it is desirable to clean the metal surface with a solvent or surfactant in advance in order to remove oil and deposits that adhere to the surface. Furthermore, if necessary, the surface can be treated with phosphate or chromate, or it can be subjected to sandblasting or shotblasting in advance. Furthermore, it is also possible to apply a primer such as an epoxy compound to the surface thus treated. By these treatments, products with very strong adhesive strength can be obtained. For coating metals, powder of the adhesive resin composition, preferably powder with a particle size of 20 to 300 μm, is used, and known powder coating methods such as fluidized dipping, electrostatic coating, and spraying are used. Laws, etc. can be applied effectively. In this case, an appropriate adhesive such as a pigment such as titanium oxide, chromium oxide or cadmium oxide is added to the adhesive resin composition, or a metal powder such as aluminum or bronze that gives metallic luster, and It is also possible to use fillers added with fillers such as magnesium oxide, calcium carbonate, and glass. Metal materials can be plate-shaped, lump-shaped, linear, rod-shaped, net-shaped,
Various shapes such as tubular, spherical, and other complex structures are used. Furthermore, the adhesive resin composition of the present invention can be used to coat the aforementioned various substrates in addition to metals, or to adhere the same or different types of substrates depending on the purpose. The coatings and laminates obtained in this way have extremely high durability as mentioned above, so they can be used, for example, in vehicles, ship parts, electromechanical parts, civil engineering/building materials, textiles, etc.
It is widely used in textile products, packaging materials, furniture, home appliances, and other household goods, and the industrial utility value of the present invention is extremely large. The present invention will be explained below with reference to examples.
The present invention is not limited thereby. In addition, each measurement value shown in this invention was measured by the following method, respectively. (1) Vinyl acetate content and saponification rate It was determined in accordance with JIS-K-6730-1977. (2) Melt index (MI) Measured at 190°C under a load of 2.16 kg in accordance with JIS-K-6760-1971. The unit of measurement value is g/
It is 10min. (3) Adhesion to steel plate A cut with a width of 25 mm was made on the steel plate coated by the fluidized dipping method, and the 180°C peel strength was measured using a tensile tester. (4) Hot water resistance test The same test pieces as in item (3) above were immersed in water maintained at 50°C and boiling water, respectively, to examine the state of the adhesive interface and changes in adhesive strength over time. (5) Salt water resistance test A test piece similar to that in item (3) above was immersed in 5% saline solution kept at 50°C, and the state of the adhesive interface and changes in adhesive strength over time were investigated. Example 1 100 weight pellets of a saponified copolymer (containing residual sodium 1200 ppm) with a saponification rate of 99% obtained by saponifying an ethylene-vinyl acetate copolymer with a vinyl acetate content of 42% by weight and a melt index of 60. % of ethylene-maleic anhydride alternating copolymer with a molecular weight of 8000 (manufactured by Monsanto, USA, EMA)
Add 0.8 parts by weight of powder of 11303) and 10 parts by weight of fine powder of titanium dioxide, and use a 30 mmφ single screw extruder.
The mixture was melt-kneaded at 140 to 150°C to obtain adhesive resin composition pellets. After cooling this composition pellet with dry ice, it is crushed with a crusher and separated to determine the particle size.
A powder of 44-250μ was obtained. This powder is placed in a fluidized bed.
70 x 150
A 3.2 mm steel plate was immersed for 10 seconds, then taken out and cooled to room temperature. The obtained coated plate has good surface gloss and
Moreover, no air bubbles were observed. Further, the thickness of the covering adhesive layer was 0.6 mm. Table 1 shows the physical property test results of this coated plate. Example 2 In Example 1, instead of the ethylene-maleic anhydride alternating copolymer, isobutylene-maleic anhydride alternating copolymer (manufactured by Kuraray Co., Ltd.) having a molecular weight of 60,000 was used.
A coated plate was obtained in the same manner as in Example 1, except that 2 parts by weight of Isoban 04) was added. The surface gloss of the obtained coated plate was good, and no air bubbles were observed. Table 1 shows the physical property test results of this coated plate. Comparative Example 1 Example 1 except that the ethylene-maleic anhydride alternating copolymer was not added in Example 1.
A coated plate was obtained in the same manner as above. Table 1 shows the physical property test results of this coated plate. Example 3 A coated plate was prepared in the same manner as in Example 1, except that titanium dioxide was not added, and physical property tests were conducted. The results are shown in Table 1. Comparative Example 2 In Example 1, a coated plate was prepared without adding the ethylene-maleic anhydride copolymer and titanium dioxide, and the results were compared with those of Example 3. The results are shown in Table 1. Example 4 Pellets of a saponified product (containing 760 ppm of residual sodium) with a saponification rate of 99% obtained by saponifying an ethylene-vinyl acetate copolymer with a vinyl acetate content of 28% by weight and a melt index of 150 were used. A coated plate was obtained in the same manner as in Example 1, except that 1.5 parts by weight of maleic anhydride alternating copolymer and 5 parts by weight of titanium dioxide were added. Table 1 shows the physical property test results of this coated plate. Comparative Example 3 Example 4 except that the ethylene-maleic anhydride alternating copolymer was not added in Example 4.
A coated plate was made in the same manner as above, and the physical properties were tested.
The results are shown in Table 1. Comparing the results of the example and comparative example above,
The initial adhesion strength at the time of coating the steel plate was all very good, and no effect of the addition of the monoolefin-maleic anhydride copolymer was observed. On the other hand, in hot water, boiling water, and saline water immersion tests, the effect is remarkable, and all of the products to which monoolefin-maleic anhydride copolymer is added exhibit strong adhesive strength over a long period of time. On the other hand, in all of the comparative examples, either the entire adhesive layer peeled off in a very short time, or a significant decrease in adhesive strength was observed. Comparative Example 4 The saponified ethylene-vinyl acetate copolymer used in Example 1 was powdered to produce a powder with a particle size of 20 to 300μ, and 100 parts by weight of this powder was mixed with the ethylene-maleic anhydride used in Example 1. Polymer powder (particle size
0.8 parts by weight (20-300μ) were mixed in a blender.
Using this powder mixture, a steel plate was coated in the same manner as in Example 1, and physical properties were tested. The results are shown in Table 1. As a result, the initial adhesive strength was as good as in Example 1, but in the hot water, boiling water, and saline water immersion tests, as in Comparative Example 1, the entire surface of the adhesive layer interface peeled off in a short period of time, or the adhesive strength was significant. A decrease in This result shows that it is necessary for the composition of the present invention to be a melt-kneaded product. Example 5 The ethylene-maleic anhydride alternating copolymer used in Example 1 was replaced with 2 parts by weight of an ethylene-maleic anhydride copolymer containing 20 mol% of maleic anhydride having a molecular weight of 35,000. , Example 1
A coated steel plate was obtained in the same manner as above. The initial adhesion of this coated plate was as good as in Example 1, and the adhesion strength after immersion in boiling water for 5 hours and in 5% saline for 5 days was 8 and 7 kg/25 mm, respectively.

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Claims (1)

[Scope of Claims] 1. A saponification rate of 50 to 50 obtained by saponifying an ethylene-vinyl acetate copolymer having a vinyl acetate content of 10 to 55% by weight and a melt index of 5 to 500.
100 parts by weight of the 100% saponified copolymer and the monoolefin and one or more unsaturated carboxylic anhydrides containing 5 to 50 mol% of the unsaturated carboxylic anhydride. Copolymer 0.01~2.5
An adhesive resin composition obtained by melt-mixing parts by weight. 2. Claim 1, wherein the vinyl acetate content of the ethylene-vinyl acetate copolymer is 15 to 50% by weight.
The adhesive resin composition described in . 3 The saponification rate of ethylene-vinyl acetate copolymer is
80 to 100% of the adhesive resin composition according to claim 1. 4. Claim 1, wherein the direct copolymer is a direct copolymer of monoolefin and maleic anhydride.
The adhesive resin composition described in . 5. The adhesive resin composition according to claim 1 or 4, wherein the direct copolymer is an alternating copolymer of ethylene or isobutylene and maleic anhydride. 6. The adhesive resin composition according to claim 1, wherein the amount of the direct copolymer added is 0.05 to 2 parts by weight. 7. The adhesive resin composition according to claim 1, wherein the adhesive resin composition is a powder.