JP3023457B2 - An ethylene-vinyl acetate copolymer hot melt adhesive composition. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to an ethylene-vinyl acetate copolymer composition useful as an adhesive or a coating composition.

[0002]

2. Description of the Related Art Saponified ethylene-vinyl acetate copolymers, for example, have excellent adhesiveness to fibers and are widely used as hot melt adhesives (Journal of the Adhesion Society of Japan: Vol. 10 No. 1P1). ~ 6 (1974), Vol.15 No.4P
10-16 (1979)). The saponified product is grafted with an ethylenically unsaturated carboxylic acid or an anhydride thereof for the purpose of improving the adhesive strength, thermal stability, etc., and is improved by a saponified grafted product of an ethylene-vinyl acetate copolymer. A law has been found (Japanese Patent Publication No. 1-28099, etc.).

Further, various methods have been proposed in which a saponified ethylene-vinyl acetate copolymer or a grafted product thereof is used in the field of powder coatings or as an adhesive for vibration damping materials (Japanese Patent Publication No. 47-10529, JP-A-61-247766, JP-A-61-24445, etc.). However, all of these known methods use a complicated method such as insufficient adhesion to a metal or glass or sandwiching another resin having a high adhesive strength, and this improvement is demanded. Was.

[004]

SUMMARY OF THE INVENTION The present inventors have used a saponified product or a saponified grafted product of an ethylene-vinyl acetate copolymer as a structural adhesive or a powder coating material, and have obtained adhesive strength, peel strength or impact strength. The above-mentioned object is achieved by adding a specific polycarboxylic acid or an anhydride thereof to a saponified ethylene-vinyl acetate copolymer or a grafted product thereof, as a result of earnest studies and studies on compositions excellent in strength and the like. This led to the completion of the present invention.

[0005]

The present invention comprises a saponified ethylene-vinyl acetate copolymer or a grafted product thereof, and one or more selected from aliphatic or aromatic polycarboxylic acids and anhydrides thereof. An ethylene-vinyl acetate copolymer-based composition characterized by comprising:

Hereinafter, the present invention will be described in detail. The saponified ethylene-vinyl acetate copolymer or the grafted product according to the present invention is obtained by saponifying a known ethylene-vinyl acetate copolymer (hereinafter abbreviated as EVA) by a known method. And a grafted product thereof is also produced by grafting the saponified product by a known method.

The EVA preferably used in the present invention has a vinyl acetate content of about 5 to 80% by weight, preferably 10 to 55% by weight and a melt index (ASTMD-1238).
Those having a range of 0.5 to 500 are mentioned.

The method for saponifying EVA may be a method produced by dissolving EVA in an organic solvent or a method comprising subjecting EVA to pellets or powder. Specifically, for example, EVA is dissolved in an aromatic hydrocarbon such as xylene, toluene or benzene, saponified using an alkali catalyst, and a poor solvent for EVA such as methanol is added to the reaction system. To precipitate the reaction,
A method of obtaining a saponified product (hereinafter referred to as EVOH) by fractionation,
In a state in which EVA powder or pellets are dispersed in a low-boiling alcohol such as methanol, ethanol, or isopropanol, saponification is carried out using an alkali catalyst, and the low-boiling alcohol and the catalyst are removed by filtration. A method of obtaining a saponified product by washing with a low-boiling alcohol is exemplified.
As the alkali catalyst used in this reaction, alkali metal alcoholates, particularly sodium methylate, sodium ethylate, alkali metal hydroxides, particularly sodium hydroxide, potassium hydroxide and the like are used.

The saponification rate of the saponified ethylene-vinyl acetate copolymer used in the present invention varies slightly depending on the application, but is at least 10%, preferably at least 30%. As the adhesive for vibration or vibration damping materials, those having a ratio of 10% to 80%, preferably 20 to 70% are preferably used.

The grafting can also be performed by a known method, for example,
Rev.Roum.Chim. 1970,15 (2), P239-45, Advan.Chem.Se
Performed by r.1969, No.91, P477-88. Specifically, EVOH obtained by the above method is dissolved in an aromatic hydrocarbon solvent such as xylene or benzene, and a hydroperoxide such as t-butyl hydroperoxide or cumene hydroperoxide or a peroxide is used. Using a polymerization initiator such as dialkyl peroxides such as benzoyl and methyl ethyl ketone peroxide, diacyl peroxide, alkylidene peroxide or azobisisobutyronitrile, to graft an ethylenically unsaturated carboxylic acid or its anhydride. To a saponified graft of ethylene-vinyl acetate copolymer (hereinafter referred to as E
VOH-g-COOH). Alternatively, a saponified powder or pellet obtained in a heterogeneous system is dispersed in a low-boiling alcohol, and an ethylenically unsaturated carboxylic acid or an anhydride thereof is grafted with a polymerization initiator. You may.

Here, as the ethylenically unsaturated carboxylic acid or its anhydride used for grafting, acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, citraconic acid, maleic anhydride, maleic anhydride, Itaconic acid, citraconic anhydride and the like can be mentioned,
These monomers can be used alone or in combination with other ethylenically unsaturated monomers such as styrene, acrylic acid or esters thereof.

The reaction temperature for the grafting may be any temperature that is higher than the decomposition initiation temperature of the radical initiator. The grafting ratio is not particularly limited, but is generally preferably in the range of 0.1 to 15% by weight.

The aliphatic or aromatic polycarboxylic acid or anhydride thereof used in the present invention is a saturated or unsaturated aliphatic polycarboxylic acid having 2 to 10 carbon atoms, 8 carbon atoms.
To 20 aromatic polycarboxylic acids or their anhydrides, and derivatives containing them, for example, esters of the polycarboxylic acids with polyhydric alcohols such as alkylene glycols.

Specifically, malonic acid, adipic acid, glutaric acid, sebacic acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid or anhydrides thereof, or Diesters of melitic acid or anhydrides thereof with ethylene glycol or triesters of glycerin;
4'-benzophenonetetracarboxylic anhydride and the like. Among these, maleic anhydride, trimellitic anhydride, itaconic acid, pyromellitic anhydride or triesters of these acids or their anhydrides with diesters of ethylene glycol or glycerin, 3,3 ′,
4,4'-benzophenonetetracarboxylic anhydride is particularly preferably used. These aliphatic or aromatic polycarboxylic acids or their anhydrides are used alone or as a mixture of two or more.

In the present invention, the method of incorporating these aliphatic or aromatic polycarboxylic acids or anhydrides thereof into a saponified ethylene-vinyl acetate copolymer or a grafted product thereof depends on the use thereof and may be a known method. Although not particularly limited, the following method is preferable.

That is, when used as a so-called reactive hot melt adhesive, the polycarboxylic acid or its anhydride is added to a saponified ethylene-vinyl acetate copolymer or its grafted product at a low temperature, preferably at 120 ° C. It is performed by mixing below.

Next, this is formed into a film, sheet, powder, pellet, or the like to obtain a product. When used as an adhesive, these molded articles are reheated to complete the reaction, and thus are used, for example, as a reactive hot melt adhesive.

When used for coatings, for example, for powder coatings, a composition obtained by adding the polycarboxylic acid or its anhydride to a saponified ethylene-vinyl acetate copolymer or its grafted product. If necessary, pigments (eg, titanium oxide, carbon black, etc.), fillers (eg, talc, calcium carbonate, etc.), stabilizers (eg, Irganox, tinuvin, etc.) leveling agents (eg, acrylic acid-based leveling agents, silicon-based) A powder coating composition can be obtained by adding a leveling agent, etc., melt-kneading with an extruder, and then pulverizing or freeze-pulverizing. After kneading with a heating roll, pulverization may be performed. In order to apply the powder coating composition to the surface of the object to be coated, a method known per se can be applied. For example, the composition is applied using a coating method such as an electrostatic coating method, a fluid immersion method, or a spraying method. .

The content of the polycarboxylic acid relative to the saponified ethylene-vinyl acetate copolymer or the grafted product thereof varies depending on the saponification rate of EVOH. 0.001 to 20% by weight, preferably 0.01 to 10% by weight of the polycarboxylic acid or its anhydride based on 100 parts of the compound
It is preferable to add by weight.

The ethylene-vinyl acetate copolymer composition of the present invention may further contain talc, charcoal,
Aluminum hydroxide, silica sand, clay, shirasu balloon,
An inorganic filler such as glass balloon, graphite, silicon carbide, and aluminum oxide can be blended, and an organic filler such as walnut shell powder and polyethylene powder can also be blended. If necessary, a coloring agent,
Known additives such as a dehydrating agent, an antifoaming agent, a plasticizer, and an antioxidant may be added.

The ethylene-vinyl acetate copolymer composition of the present invention is particularly useful as a hot melt adhesive.
For example, as an adhesive applied between various substrates such as glass-to-glass, metal-to-metal, glass-to-metal, glass-to-plastic, metal-to-plastic, or fiber-to-fiber, or fiber-to-plastic, particularly automobiles, aircraft, building materials, clothing, communications, etc. Widely used in industrial fields.

It has been found that the ethylene-vinyl acetate copolymer composition of the present invention is used as a coating composition for glass, metal and plastic, and has excellent performance especially as a powder coating.

The ethylene-vinyl acetate copolymer composition of the present invention has particularly good damping properties and excellent adhesive strength, and is therefore preferably used as a damping adhesive. Regarding the vibration damping properties of resin, for example, see “Iron and steel” 72 (198
6) No. 10, as described in P1575-1581, it is known that the mechanical loss tanδ obtained by measuring the viscoelasticity of a resin is closely related to the vibration damping property. And of many resins
From the measurement results of tan δ, if tan δ is 0.1 or more, it is estimated to have good vibration damping properties (Japanese Patent Laid-Open No. 3-7792), but the composition of the present invention satisfies these requirements,
And it has excellent adhesive strength.

Further, the ethylene-vinyl acetate copolymer composition of the present invention is used as an adhesive between a honeycomb structural material core such as aluminum and paper and a surface material, or applied to the fields of elastic grindstones and nonwoven fabrics. Is preferably used for applications such as a compatibilizer for polymer alloys.

[0025]

The composition of the present invention has high peel strength, excellent impact strength, vibration damping properties and excellent heat resistance, and is particularly excellent as a structural adhesive, fiber adhesive or powder coating. I have. In particular, the composition of the present invention exhibits excellent effects as a reactive hot melt adhesive or paint.

[0026]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Synthesis Example 1 Synthesis of EVOH by Homogeneous Reaction A stirrer, a thermometer, a cooling tube, and a nitrogen inlet tube were installed in a 10-liter flask, and the inside of the flask was replaced with nitrogen gas. Then, 3000 parts of xylene and methanol were added to the flask. 1000 copies and EV
A (vinyl acetate content 40% by weight, MI: 60 g / 10
min.) 1000 parts, heated to 45 to 50 ° C., and after confirming complete dissolution, 28% sodium methoxide-
After adding 35 parts of a methanol solution and reacting at 45 to 50 ° C. for 60 minutes, 270 parts of water was added to stop the reaction,
After cooling to room temperature, the reaction product was taken out and methanol 2500
The polymer was taken out by a reprecipitation method by introducing the mixture into a mixer containing the parts. The saponification ratio of the obtained saponified product was 55%.

Synthesis Example 2 Synthesis of EVOH by Heterogeneous Reaction A stirrer, a thermometer, a cooling tube, and a nitrogen inlet tube were installed in a 10 L flask, and the inside of the flask was replaced with nitrogen gas. Then, 6000 parts of methanol was added to the flask. And EVA in pellet form (vinyl acetate content 40% by weight, MI: 60 g / 10 min.)
Add 2500 parts, add 160 parts of methanol solution of sodium methoxide at 30 ° C or lower, react at 45 to 50 ° C for 5 hours, cool to 40 ° C or lower, filter, separate the pellets and take out the reaction product. Washed twice with 6000 parts of methanol to obtain EV-OH having a saponification rate of 53%.

Synthesis Example 3 Synthesis of EVOH-g-COOH by Homogeneous Reaction A stirrer, a thermometer, a cooling tube, and a nitrogen inlet tube were installed in a 1-L flask, and the inside of the flask was replaced with nitrogen gas. And the EV-OH obtained in Synthesis Example 1.
Charge 100 parts and raise the temperature to 120 ° C, dissolve uniformly,
1.5 parts of acrylic acid was added, then 0.2 parts of azobisisobutyronitrile (hereinafter abbreviated as AIBN) was added, the mixture was kept warm for 1 hour, cooled to 50 ° C, and then stirred with methanol. Then, EVOH-g-COOH was precipitated.

Synthesis Example 4 Synthesis of EVOH-g-COOH by Heterogeneous Reaction A 1-L flask was equipped with a stirrer, a thermometer, a cooling tube, and a nitrogen inlet tube. After the inside of the flask was replaced with nitrogen gas, methanol was added to the flask. -500 parts of EVOH obtained in Synthesis Example 2
After 100 parts were charged, the temperature was raised to 50 ° C., and the mixture was uniformly dissolved, 2.5 parts of acrylic acid was added, and then azobisisobutyronitrile (hereinafter abbreviated as AIBN) 0.2.
The mixture was charged for 9 hours, cooled to 40 ° C., and filtered to remove the polymer by filtration to precipitate EVOH-g-COOH.

Synthesis Example 5 Synthesis of EVOH by Heterogeneous Reaction In Synthesis Example 2, a mixture of pelletized EVA (vinyl acetate content 40% by weight, MI: 60 g / 10 min.) And methanol solution of natrium methoxide was used. The reaction is
The reaction was carried out in the same manner except that the reaction was carried out at 45 to 50 ° C. for 12 hours.
VOH was obtained.

Examples 1-5 EVOH or EVOH-g- synthesized by the above method
Using COOH, preparation of the samples described below and measurement of the adhesive strength were performed.

Preparation of sample [ Preparation of pellet] EVOH or E obtained in the synthesis example
A predetermined amount of pyromellitic anhydride shown in Table 1 was weighed into VOH-g-COOH, and the amount was measured using a small extruder for experiment.
The mixture was melt-mixed at 00 ° C. to form pellets.

[Preparation of Sheet] The pellets obtained above were squeezed into a sheet having a thickness of 0.2 mm by using a hot press molding machine.
It was made at a molding temperature of 0 ° C.

Measurement of Adhesion Strength [Sample for Peel Strength Measurement] A sheet formed between two pieces of aluminum (JIS H 4000 A1050P) adjusted to a size of 0.3 mm × 25 × 150 is sandwiched between sandwiches. 170 ° C
For 10 minutes at the contact pressure.

[Sample for heat resistance test] 1.5 mm × 25 × 100
A sheet of 0.2 mm was sandwiched in a 25 mm × 25 area between two pieces of aluminum adjusted to the above-mentioned sizes and bonded at 170 ° C. for 10 minutes by contact pressure.

[Measurement of Peeling Strength] Using an autograph manufactured by Shimadzu Corporation, the crosshead speed was 50 mm / min.
A T-type peeling test was performed in a constant temperature and humidity chamber at a temperature of ℃. (Unit: kg
/ inch)

[Heat Resistance Test] A weight of 25 g was hung on the end of the sample for heat resistance test, and the sample was placed vertically in an oven at 100 ° C.
After hanging for 0 minutes, the displacement of the test piece was measured (unit: mm).
The results are shown in Table 1. For comparison, a case where the polycarboxylic acid of the present invention or the anhydride thereof was added without addition was also described as Comparative Example 1.

[0039]

[Table 1]

^{* 1 The} amount of the polycarboxylic acid described in Table 1 is EVOH or EVOH-g-COOH 100
Parts. ^{* 2} RIKACID TMEG is a trade name of ethylene glycol bis (anhydrotrimellitate) from Shin Nippon Rika Co., Ltd.

Examples 6 to 17 EVOH-g of various saponification ratios were prepared in substantially the same manner as in Synthesis Example 3.
-COOH was synthesized, a predetermined polycarboxylic acid or an anhydride thereof was added in the same manner as in Examples 1 to 5, and the measurement results are shown in Tables 2 and 3. Shown in

[0042]

[Table 2]

[0043]

[Table 3]

Example 18 The EVOH obtained in Synthesis Example 5 was pulverized, and
1 part by weight of pyromellitic anhydride was added to 100 parts by weight of powder EVOH having an average particle diameter of 168 μm from which mesh on was removed, and the mixture was thoroughly mixed to sufficiently disperse pyromellitic anhydride. This is 30cm wide, 80cm long, 100cm high
The fluidized bed was charged to a height of 45 cm into a fluidized bed box, and a fluidized bed was formed so that the height of 70 cm was uniformly maintained by clean air.

Then, the sample was allowed to stand still for 3 minutes in a heating furnace preheated to an internal temperature of 250 ° C. for 90 mm × 110 mm ×
A sand blasted steel plate of a test piece having a size of 2 mm was quickly immersed in the above fluidized bed and held for 3 seconds, and then the coated test piece was taken out. After another 20 seconds, the test piece was immersed in cold water and rapidly cooled. The coating film of the obtained test piece was smooth and glossy.

A cut was made with a knife so as to form a total of 100 grooves, 10 horizontal and 10 vertical, at 1 mm intervals on the steel plate coating film. A so-called gobang test was conducted in which the cellophane tape was pulled up from the steel plate in a vertical direction. The number of grooves on the side of the cellophane tape was 0/100, indicating good adhesion of the coating film.

For comparison, a coating film test piece similar to the above was prepared without the addition of pyromellitic anhydride, and a 7/100 gobang was cut on the side of the cellophane tape by the same gobang test.

Example 19 The EVOH obtained in Synthesis Example 1 was pulverized, and
1 part by weight of pyromellitic anhydride was added to 100 parts by weight of powder EVOH having an average particle diameter of 143 microns from which mesh on had been removed, and thoroughly mixed to sufficiently disperse pyromellitic anhydride. This was charged to a height of 45 cm in a fluidized bed box having a width of 30 cm, a length of 80 cm and a height of 100 cm, and a fluidized bed was formed so that the height of 70 cm was uniformly maintained by clean air.

Then, the sample was allowed to stand for 3 minutes in a heating furnace preheated to an internal temperature of 250 ° C. for 90 mm × 110 mm.
A sand-blasted steel plate of a test piece having a size of 2 mm was quickly immersed in the fluidized bed and held for 3 seconds, and then the coated test piece was taken out. After another 20 seconds, the test piece was immersed in cold water and rapidly cooled. The coating film of the obtained test piece was smooth and glossy.

A cut was made with a knife on the steel plate coating so as to form a total of 100 horizontal bars and 10 vertical bars at 1 mm intervals. A so-called gobang test was conducted in which the cellophane tape was pulled up from the steel plate in a vertical direction. The number of grooves on the side of the cellophane tape was 0/100, indicating good adhesion of the coating film.

For comparison, a coating film test piece was prepared in the same manner as described above without the addition of pyromellitic anhydride, and a 12/100 gobang pattern was obtained on the side of the cellophane tape by the same gobang test.

Example 20 1 part by weight of pyromellitic anhydride was added to 100 parts by weight of the EVOH obtained in Synthesis Example 2, and 10 parts by weight of a small extruder was used.
The mixture was melt-mixed at 0 ° C. to form pellets. The obtained pellets were formed into a 1 mm thick sheet by a hot press molding machine.
It was produced at a molding temperature of ° C.

This sheet was treated with FT Rheospectra DVE-
When the viscoelasticity was measured with a V4 type (manufactured by Rheology), t
The temperature range where an δ exceeds 0.1 was −15 ° C., indicating good vibration damping properties.

A sheet having a thickness of 80 μm was prepared from the above pellets, and this sheet was sandwiched between mild steel sheets having a thickness of 0.3 mm.
The thermocompression bonding was performed at 190 ° C. for 5 minutes at 30 kg / cm ² . The adhesive strength was 28 kg / inch in peel strength. For comparison, when a similar sheet was prepared without adding pyromellitic anhydride, the adhesive strength was 11 kg / inch in peel strength.

Example 21 1 part by weight of pyromellitic anhydride was added to 100 parts by weight of the EVOH-g-COOH obtained in Synthesis Example 4, and the mixture was melt-mixed at 100 ° C. using a small extruder to form pellets. did. The obtained pellet is 1mm thick by hot press molding machine
At a molding temperature of 100 ° C.

This sheet was treated with FT Rheospectra DVE-
When the viscoelasticity was measured with a V4 type (manufactured by Rheology), t
The temperature range where an δ exceeds 0.1 was −17 ° C., indicating good vibration damping properties.

A sheet having a thickness of 80 μm was prepared from the above pellets, and was sandwiched between mild steel sheets having a thickness of 0.3 mm.
The thermocompression bonding was performed at 190 ° C. for 5 minutes at 30 kg / cm ² . The adhesive strength was 42 kg / inch in peel strength. For comparison, when a similar sheet was prepared without adding pyromellitic anhydride, the adhesive strength was 18 kg / inch in peel strength.

──────────────────────────────────────────────────続 き Continuation of front page (51) Int.Cl. ⁷ Identification symbol FI C09J 151/06 C09J 151/06 (56) References JP-A-61-243874 (JP, A) JP-A-61-243875 (JP) JP-A-61-247766 (JP, A) JP-A-61-24445 (JP, A) JP-B-47-11901 (JP, B1) JP-B-47-10529 (JP, B1) (58) Field surveyed (Int.Cl. ⁷ , DB name) C08L 23 / 26,29 / 04,51 / 06 C09J 123 / 26,129 / 04,151 / 06

Claims (3)

(57) [Claims] 1. A saponified ethylene-vinyl acetate copolymer having a saponification ratio of 10% to 80% or a grafted product thereof, and one or more selected from aliphatic or aromatic polycarboxylic acids and anhydrides thereof. 0.001 ethylene, characterized in that comprising 20 wt% - vinyl acetate copolymer e
A melt adhesive composition. However, hot melt for fiber materials
Excluding glue. 2. The ethylene-vinyl acetate copolymer hot melt adhesive composition according to claim 1 , wherein a saponified graft product of an ethylene-vinyl acetate copolymer is used. 3. The method according to claim 1, wherein the aliphatic or aromatic polycarboxylic acid or anhydride thereof is maleic anhydride, trimellitic anhydride, itaconic acid, pyromellitic anhydride or a diester of these acids or anhydrides and ethylene glycol. Triesters with glycerin, 3,3 ', 4
The ethylene-vinyl acetate copolymer hot melt adhesive composition according to any one of claims 1 and 2 , wherein the composition is selected from 4'-benzophenonetetracarboxylic anhydride.