JPH01221475A - Adhesive composition - Google Patents

Abstract

PURPOSE:To obtain the title composition economically without the necessary for washing with an organic solvent, by grafting a polyolefin resin with maleic acid (anhydride) and a styrenic monomer under specified conditions. CONSTITUTION:A polyolefin resin (e.g., PE) is dissolved by heating in an organic solvent (e.g., xylene) in an amount sufficient to provide a resin content of 1-25wt.%. This resin is grafted with 0.25-50pts.wt., based on 100pts.wt. said resin, substantially equimolar mixture of maleic acid (anhydride) with a styrenic monomer (e.g., styrene), i.e. in a molar ratio of 0.8-1.1, in the presence of 0.5-5pts.wt., based on 100pts.wt. said resin, radical generator (e.g., benzoyl peroxide), and then cooled under agitation to deposit fine particles of the modified resin from the solution thereof.

Description

Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention provides an adhesive composition useful as an adhesive between a metal and a polyolefin, which contains a modified polyolefin resin dispersed in an organic solvent. For more information on roll coater
The present invention relates to an adhesive composition that has good coating properties and excellent adhesive properties, and a manufacturing method that can economically advantageously produce the composition.

(Prior Art) Carboxyl group-modified polyolefin resins are known as adhesives between metals and polyolefins.

To produce this modified polyolefin resin, a mixture of an ethylenically unsaturated carboxylic acid such as maleic anhydride or a radically polymerizable monomer containing an ethylenically unsaturated carboxylic acid is added to the polyolefin resin in the presence of a radical generator. Make a graft reaction.

As typical modification methods, a method is known in which a polyolefin resin raw material is kneaded in a molten state and reacted with a radically polymerizable monomer, and a method in which a polyolefin resin is dissolved in an organic solvent and reacted in a solution state. The former method allows the production of modified resins economically because it does not use organic solvents, but it has the disadvantage of difficult to control the graft reaction, and unreacted monomers may be mixed in as impurities. It is inevitable that
For this reason, adhesive strength is poor and there are also hygiene problems due to the presence of impurities. Therefore, the adhesive obtained by this method cannot be applied to food container applications.

The method of grafting a radically polymerizable monomer to a polyolefin resin raw material dissolved in an organic solvent is easy to control in one reaction.

As expected, there are unreacted monomers or polymers that do not contribute to grafting, resulting in poor adhesion.

Hygiene issues still remain. For this reason, the Tokuko Sho 6
As disclosed in Japanese Patent Application Laid-open No. 0-225 and Japanese Patent Application Laid-Open No. 16391.1, after separating the modified resin from the organic solvent, an organic solvent is used to remove these impurities. It is necessary to wash with 4 fl. However, a large amount of organic solvent is used for this purpose.

Although the modified polyolefin resin obtained by this method has excellent performance, it has been subject to economical constraints.

On the other hand, methods for applying a carboxyl group-modified polyolefin resin adhesive to a base material such as a metal plate include a method of applying the modified resin in a molten state, an electrostatic coating method as a powder coating7,
``A method of painting by fluidized dipping and a method of fusing as a sheet-like material are also known.

These methods require special equipment and are uneconomical as they inevitably make the adhesive layer thicker than necessary.

For this reason, it has been proposed to make a modified polyolefin resin into a dispersion in an organic solvent and apply this composition to a substrate using a coating device such as a roll coater. However, a composition in which a modified polyolefin resin is simply a dispersion of an organic solvent has the drawback of extremely poor coating properties. For this purpose, as disclosed in Japanese Patent Application Laid-Open No. 13342/1983.

It has also been proposed to improve the coatability of the composition by incorporating a soluble resin such as an epoxy resin.

According to this technology, the coating properties of the adhesive composition are improved,
In addition, although an adhesive with good performance can be obtained, there still remains the problem of economic efficiency due to the necessity of washing the modified resin.

(Problems to be Solved by the Invention) The present invention provides an economically advantageous adhesive composition that eliminates the need for cleaning with an organic solvent when producing a carboxyl group-modified polyolefin resin.

Another object of the present invention is to provide an adhesive composition with good surface properties when coated with a roll coater.

Furthermore, the present invention provides an adhesive composition that firmly adheres between a metal and a polyolefin.

Furthermore, the present invention provides an adhesive composition that contains almost no monomer impurities and has excellent hygiene properties.

[Structure of the invention]

(Means for Solving the Problems) The present invention provides a method of combining a polyolefin resin dissolved in an organic solvent with substantially equimolar amounts of maleic anhydride or maleic acid and a styrene-based polymer in the presence of a radical generator. This invention relates to an adhesive composition obtained by graft-modifying the modified resin and precipitating fine particles of the modified resin from the resulting modified resin solution, and a method for producing the adhesive composition.

The polyolefin resin in the present invention refers to a homopolymer of ethylene or propylene, an ethylene-propylene copolymer, or ethylene or propylene and other olefins, such as 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 4-methyl-1-
Contains copolymers of pentene and 1-decene. Furthermore, a copolymer of an olefin and a different monomer, such as an ethylene-vinyl acetate copolymer, can be used as the polyolefin resin.

The radical generator in the present invention is a common initiator for radical polymerization, and refers to a substance that is easily decomposed by heat, light, etc. and generates active radicals that can initiate polymerization. Persulfates such as ammonium persulfate as peroxides,
Hydroperoxides such as hydrogen peroxide, t-butyl hydroperoxide, cumene hydroperoxide,
peroxyketals such as 2,2-bis(t-butylperoxide')octane, dicumyl peroxy F,
Dialkyl peroxides such as t-butylcumyl peroxide and di-cumyl peroxide, diasilver oxides such as octanoyl peroxide, decanoyl peroxide, lauroyl peroxide and hensyl peroxide, diisopropyl peroxide carbonate,
Peroxide carbonates such as di(2-ethylhexyl) peroxide carbonate, peroxy esters such as t-butyl peroxyisobutyrate and t-butyl peroxyhenshade, 2゜2'-azobisisobutyrate Azo compounds such as lonitrile.

Mixtures such as copper, iron powder and henzyl chloride, letosox initiators using combinations of oxidizing agents and reducing agents, further using organometallic compounds such as metal alkyls, combinations of metal alkyls and oxygen donors or metal halides, or alkylperoxy metals. be able to. These radical generators are selected depending on conditions such as the organic solvent used in the graft reaction and the reaction temperature. In the present invention, the temperature at which the graft reaction is carried out by dissolving the polyolefin resin in an organic solvent9 is, for example, 100 to 150'. For C, those with a half-life of about 1 minute are suitable, such as hensyl peroxide 2, lauroyl peroxide, 1,1-bis(L-butylperoxy)3.3.5-)limethylcyclohexane, t-
Butylperoxy (2-ethylhexanonyi), 2°2'-abbisisobutyronitrile and the like are preferred.

The amount of the radical generator used in the present invention is 05 to 5 parts, preferably 1 to 5 parts, per 100 parts of the polyolefin resin used.
Three parts are used.

1 The organic solvent used in the present invention is a solvent that can dissolve the polyolefin resin under heating and perform a graft reaction, and is suitable for precipitating fine particles of the modified resin from the obtained modified resin solution. It is. Such organic solvents include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone.

Ketones such as isophorone, aromatic hydrocarbons such as henzene, toluene, xylene, and other alkylhenzene,
Appropriate selection from cellosolves such as methyl cellosolve, ethyl cellosolve, butyl cellosolve, esters such as methyl cellosolve acetate, butyl cellosolve acetate, ethyl acetate, butyl acetate, alcohols such as isopropyl alcohol, butyl alcohol, diacetone alcohol, etc. However, if necessary, these mixed containers may be used.

In the present invention, the polyolefin resin is heated and dissolved in an organic solvent to perform a graft modification reaction. The ratio of polyolefin resin and organic solvent used is 1 to 25% by weight as the concentration of modified polyolefin resin at the end of the grafting reaction;
Preferably, the ratio is 1 to 15%. If the proportion of the polyolefin resin used is too high, the concentration of the reaction solution 9 will become high, resulting in non-uniform grafting reactions, or when the fine particles of the modified resin are precipitated from the solution of the modified resin in the 1st reaction, the 2nd composition will gel. This will result in the coating becoming impossible to coat on the substrate.

The monomer to be graft-modified to the polyolefin resin in the present invention is maleic anhydride or maleic acid and a styrene monomer. Styrene monomers include styrene, α-methylstyrene, chlorostyrene, cyanostyrene, aminostyrene, hydroxystyrene, vinyltoluene, divinylhenzene, and the like.

The amounts of maleic anhydride or maleic acid and the styrene monomer used are substantially equimolar. ,0
．． 9 to 1.05. The total amount of monomers used is 0.25 to 5 parts per 100 parts of the polyolefin resin used.
0 parts, preferably 3 to 40 parts are used. When the amount of monomer used is more than 50 parts.

A large amount of polymerized monomers that do not contribute to graft modification tend to be produced, resulting in a decrease in adhesive strength.

In the present invention, as a method for graft-modifying a polyolefin resin, a polyolefin resin, maleic anhydride, styrene, and a radical generator are added to an organic solvent 1, such as xylene, and heated to dissolve and react the polyolefin resin. Alternatively, there is a method in which polyolefin resin, maleic anhydride, and styrene are heated and melted in an organic solvent, and a radical generator is added at a constant rate at a constant temperature. This method maintains a constant radical concentration in the reaction system. It is effective for More specifically, 1, for example, 40 to 100 parts by weight of xylene, 1 to 20 parts by weight of a polyolefin resin such as polypropylene, and substantially equimolar amounts of maleic anhydride or maleic acid and styrene monomer in a total amount of 0.05 to 10 parts by weight. At 130°C with weight parts added? Dissolve and add Henzoyl Peroxiside 0.01 to 1.
A solution of 0 parts by weight dissolved in 10 to 30 parts by weight of xylene is added dropwise over a period of 1 hour, and after adding 1 drop, the reaction is further stirred for 1 hour to complete the reaction.

In the adhesive composition of the present invention, a resin dispersion can be formed by cooling the modified resin solution obtained by the graft reaction with stirring and precipitating fine particles of the modified resin. Furthermore, when precipitating fine particles of the modified resin, it is also effective to add another organic solvent or to add the modified resin solution to another organic solvent while stirring.

In the present invention, coating properties and adhesive performance can be further improved by adding a soluble resin to the modified resin dispersion obtained by the above method. Suitable examples of these soluble resins include those that can be dissolved in a resin dispersion solution and have adhesive properties with the graft-modified polyolefin resin after heating and drying. For example, epoxy resins with a molecular weight of 1500 or more, ethylene-vinyl acetate copolymer resins, acrylic resins, polyester resins, henzoguanamine resins, phenolic resins,
A urea resin or a mixture thereof can be used. In particular, by combining an epoxy resin and a curing agent resin for the epoxy resin such as a phenol resin or an amino resin, it is possible to further improve the coatability of one composition and improve the corrosion resistance of the metal substrate. .

The amount of the soluble resin that can be blended is at most 10 times, preferably at most 5 times, the amount of the modified polyolefin resin on a weight basis.

The soluble resin can be added to the reaction solution during the grafting reaction, added after the grafting reaction is completed and cooled with stirring, or added while stirring the grafting reaction solution into the soluble resin solution. There are ways to add it.

The adhesive composition of the present invention is applied to a base material such as metal.

When the modified polyolefin is polyethylene, 150~
200°C, 180-220 for polypropylene
The organic solvent is removed by heat treatment at a temperature of .degree. C., and the modified polyolefin resin is melted to form an adhesive layer. The base materials include treated steel plates such as tin-free steel, various galvanized steel plates, and aluminum plates.

There are copper plates etc. The coating can be applied to the base material by using a roll coater, but other methods such as spray coating and flow coating may also be used. The thickness of the adhesive layer is 1-1
It is 0μ, preferably 3 to 5μ.

For the adhesive layer formed on the metal substrate, a metal-polyolefin laminate is produced by fusing molten polyolefin resin or by pressurizing and heating a polyolefin film. The temperature conditions for laminating polyolefin films are 150 to 200 for polyethylene.
°C1 and 180 to 220 °C for polypropylene. The metal-polyolefin laminate thus obtained can be used as a material for packaging containers and the like. Furthermore, the adhesive composition of the present invention can be used as an adhesive having a metal protective coating function for metal-plastic film composite containers and the like.

(Operations and Effects of the Invention) It is known that maleic anhydride or maleic acid and a styrene monomer form an alternating copolymer through radical polymerization.

In the present invention, since the polyolefin resin is graft-modified using maleic anhydride or maleic acid and a styrene monomer, it is thought that the graph 1 chain of the alternating copolymer is formed. For this reason, unlike graft modification with maleic anhydride or maleic acid, in which homopolymerization hardly occurs.

It is thought that the modified polyolefin resin of the present invention forms a graph +-tX with a long chain length, and as a result, the affinity for organic solvents increases, resulting in improved coatability.

Furthermore, in the present invention, maleic anhydride or maleic acid and styrene monomer are used in substantially equimolar amounts in graph 1 to modification. Because both monomers react quickly to form an alternating copolymer.

The amount of unreacted monomer that does not adversely affect the adhesive force is extremely small, therefore, the adhesive force is large and there are no hygiene problems caused by unreacted residual monomers.

According to the method for producing an adhesive composition of the present invention, there is no need to wash the modified polyolefin resin with an organic solvent, remove unreacted monomers, etc., and purify the modified polyolefin resin. A solvent dispersion of the resin can be obtained.

(Example) The present invention will be explained below with reference to Examples. 1 part means part by weight, and 1% means % by weight.

Example 1 In a reaction vessel equipped with a stirrer, a cooler, two dropping tubes, and a nitrogen inlet tube, 480 parts of xylene, 80 parts of polyethylene resin (Ultozex 30200J manufactured by Mitsui Petrochemical Industries, Ltd.),
7.76 parts of maleic anhydride and 8.24 parts of styrene (styrene/maleic anhydride molar ratio 1°0; hereinafter, St/M
(denoted as AA=1.0) and heat to melt to 130
It was kept at °C. A solution prepared by dissolving 0.8 parts of hensyl peroxide in 240 parts of xylene was added dropwise to this solution with stirring over a period of 1 hour to carry out a reaction. After addition, stirring was continued for 1 hour.

While stirring, the mixture was gradually cooled to room temperature to precipitate fine particles of the modified resin, thereby obtaining an adhesive composition.

Implementation examples 2 and 3 Xylene added into the reaction vessel in Example 1.

The amounts of polyethylene, maleic anhydride, styrene, and hensyl peroxide added were changed as follows.

An adhesive composition was obtained in the same manner as above.

Example 2 Example 3 Xylene 560 parts 240 parts Polyethylene 8 parts 160 parts Maleic anhydride 0.19 parts 38.8 parts Styrene 0.21 parts 41.2 parts Hensil Veroxy I'' 0.08 parts 8 parts St/ M.A.
A 1.0 1.0 Example 4 In Example 1, ethylene resin was used instead of polyethylene resin.
An adhesive composition was obtained in the same manner except that 80 parts of butene-1 copolymer resin (Neozenox 45200 manufactured by Mitsui Petrochemical Industries, Ltd.) was used.

Example 5 In Example 1, ethylene resin was used instead of polyethylene resin.
40 parts of butene-1 copolymer resin (Neozesoku 4520〇 manufactured by Mitsui Petrochemical Industries, Ltd.) and 4 parts of ethylene-vinyl acetate copolymer (Nohatesoku APL32B manufactured by Mitsubishi Chemical Industries, Ltd.)
An adhesive composition was obtained in the same manner except that 0 part was used.

Examples 6 and 7 Adhesive compositions were obtained in the same manner as in Example 1, except that the amounts of maleic anhydride and styrene added to the reaction vessel were changed as follows.

Example 6 Example 7 Maleic anhydride 8.65 parts 7.38 parts Styrene 7.34 parts 8.62 parts St/MAA 0.8 1.1
Example 8 An adhesive composition was obtained in the same manner as in Example 1 except that polypropylene resin (Tinsopolybro KIO14, manufactured by Chisso Corporation) was used instead of polyethylene resin.

Examples 9 and 10 15 - Same procedure as in Examples 1 and 8 except that 9.19 parts of maleic acid was used instead of maleic anhydride.

Adhesive compositions of Example 9 and Example 10 were obtained.

Example 11 An adhesive composition was obtained in the same manner as in Example 1, except that 9.35 parts of α-methylstyrene (molar ratio of α-methylstyrene to maleic anhydride: 1.0) was used in place of the styrene used in Example 1. Ta.

Example 12 Epoxy resin (
Epicote 1009. A melt of 50 parts of Yuka Shell Epoxy ■) dissolved in 50 parts of cyclohexanone. At night, 50 parts of the mixture was added and stirred to prepare an adhesive composition.

Examples 13 and 14 100 parts of the evoquino resin solution used in Example 12 was heated at 50°
Solution 5 synthesized under the conditions of Example 3 and Example 8 and in a state before the modified resin precipitates was added to this while stirring as below C.
Example 13 with the addition of 0 parts. An adhesive composition of Example 14 was obtained.

Comparison Examples 1 and 2 Example 1. Comparative Example 1 was prepared under the same conditions except that styrene was not used in Example 8. An adhesive composition of Comparative Example 2 was obtained.

Comparative Examples 3 and 4 Comparative Example 1. 100 parts of methyl ethyl ketone was added to 100 parts of the modified resin obtained in Comparative Example 2 to precipitate the modified resin, which was then filtered. Furthermore, the filtrate was repeatedly washed 5 times with 50 parts of methyl ethyl ketone and dried.

Comparative Example 3 was prepared by adding 90 parts of xylene to 10 parts of each of the dried modified resins and heating and melting them, followed by stirring and cooling to precipitate the modified resin. An adhesive composition of Comparative Example 4 was obtained.

Comparative Example 5 An adhesive composition was obtained by graft modification under the same conditions as in Example 1 except that 6.84 parts of maleic anhydride and 9.16 parts of styrene (s t /MAA = 1.26) were used. .

Comparative Example 6 An adhesive composition was obtained by graft modification under the same conditions as in Example 1 except that 9.18 parts of maleic anhydride and 6.82 parts of styrene (St/MAA=0.7) were used.

Coating test and adhesion test Using the adhesive compositions obtained in Examples and Comparative Examples.

0.32mm thick tin free steel (TFS) 2
Coat it on a 00x300mm test piece using a natural roll coater to a coating thickness of approximately 5μ, dry at 180°C for 3 minutes, and then immediately heat-bond a 0.2mm thick polyethylene film or polypropylene film with a rubber roll. did. The adhesive composition of the comparative example had poor coating suitability, so it was also applied by flow coating. The adhesive strength of the TFS-polyolefin film laminated steel plate thus created was determined by the Erichsen test of 7 mm, in which valve shapes at 5 mm intervals were cut with a knife from the top of the film, and this was further submerged in boiling water for 5 hours. After immersion, the adhesion of each was observed. The results are shown in Table 1.

Explanations of symbols and terms in Table 1 are as follows.

Coating properties A: As good as normal paints Coating suitability Slightly inferior to BAA, but roll coatable Oil-based film PE: Polyethylene film PP: Polypropylene film Valve-shaped Erichsen protrusion No abnormality: Valve-shaped protrusion caused by forced peeling Peeling that cannot be exposed: The valve-shaped convex part peels off easily.As is clear from Table 1, the adhesives of Comparative Examples 1 and 2 show almost no adhesive strength under normal conditions, but the adhesives of Comparative Examples 3 and 4 The following shows the adhesion strength that leads to film breakage.

It was shown that the unreacted substance 1 reaction by-product greatly influenced the adhesion. However, dispersions of these adhesive compositions have low viscosity and poor roll coating suitability. On the other hand, in the adhesive composition of the present invention, both the state adhesive strength and the processed adhesive strength showed adhesive strength leading to film breakage, even though the reaction product was not washed. It also had good suitability for roll coating.

Further, in the adhesive compositions of Comparative Examples 5 and 6, the ratios of maleic anhydride and styrene used were not substantially equimolar, and therefore only a low level of adhesiveness was obtained.

Claims (1)

[Claims] 1. A polyolefin resin dissolved in an organic solvent is graft-modified using substantially equimolar amounts of maleic anhydride or maleic acid and a styrene monomer in the presence of a radical generator. An adhesive composition obtained by precipitating fine particles of the modified resin from the obtained modified resin solution. 2. A method for producing the adhesive composition according to claim 1. 3. The adhesive composition according to claim 1, further comprising a soluble resin. 4. The adhesive composition according to claim 3, wherein the soluble resin is an epoxy resin.