JPH0346514B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing an adhesive film using a hot-melt adhesive composition, and more particularly to an adhesive composition containing an unsaturated carboxylic acid graft modified product of ethylene/α-olefin copolymer rubber as an essential component. The present invention relates to a method for producing an adhesive film using. Traditionally, adhesives in adhesive tapes, etc. are usually made of elastomers such as polyisoprene, styrene-butadiene rubber, butyl rubber, polyisobutylene, chloroprene rubber, polyacrylic acid ester, polyvinyl ether, rosin and its derivatives, terpene resin, petroleum resin, coumaron indene, etc. It consists of a tackifier such as a resin, and if necessary, a softener, a filler, an anti-aging agent, etc. Most of these adhesives are once dissolved in an organic solvent and then applied to a support. applied. However, in recent years, there has been a desire to eliminate solvents from the viewpoint of pollution control or working environment, and the amount of hot melt adhesives used has increased. Traditionally, the adhesive properties of adhesives have been evaluated based on three characteristics: (a) tack (instantaneous adhesion), (b) adhesion (peel resistance), and (c) retention (slip resistance). Currently, styrene-isoprene-styrene block copolymer rubber (SIS) and styrene-butadiene-styrene block copolymer rubber (SBS) are used as elastomers that satisfy these characteristics to a certain extent. The problem with this rubber is that it has poor heat resistance and weather resistance. In addition, hot melt adhesives are applied to the base material using an applicator, but conventional hot melt adhesive applicators are mainly used for applying low viscosity adhesives, so hot melt adhesives have their adhesive strength adjusted accordingly. The main focus was on developing adhesives with low viscosity and good spreadability at the expense of adhesive strength and retention. However, such hot melt type adhesives tend to lack strength and heat resistance compared to solvent-based or emulsion-based adhesives, and it is desired to improve these properties by increasing the viscosity. Recently, coating machines such as extrusion coating and extrusion lamination methods that can apply high-viscosity hot melt adhesives at high speed, or methods that co-extrude the base material and adhesive to make adhesive tapes, etc. have been developed. There is a high demand for hot melt adhesives suitable for An object of the present invention is to provide a method for producing an adhesive film that has excellent tack, adhesive strength, and holding power, and has good heat resistance. It is an object of the present invention to provide a method for producing an adhesive film suitable for coating or laminating on materials. That is, the present invention provides an ethylene/α-olefin modified copolymer having a melt index of 0.01 to less than 5, which is obtained by graft-modifying an ethylene/α-olefin copolymer having an ethylene content of 40 to 85 mol% with an unsaturated carboxylic acid or a derivative thereof. An adhesive composition comprising 30 to 70% by weight of copolymer rubber and 70 to 30% by weight of terpene resin or alicyclic or aliphatic petroleum resin is applied to a base material or laminated with the base material. This is a method for producing an adhesive film. The ethylene-α-olefin copolymer rubber used as a raw material for the modified rubber in the present invention is substantially saturated and does not contain polyene components such as dienes and trienes in the polymer chain, or even if it does contain it. Very little, for example less than 0.5 mole %, of rubbery material. In other words, if ethylene copolymer rubber with many unsaturated bonds, such as EPDM, which is commonly available on the market, is used as a raw material,
Since only a modified product having a high gel content and poor fluidity even at high temperatures can be obtained, it cannot be applied to a support and the object of the present invention cannot be achieved. The ethylene content of the copolymer rubber is preferably 40 to 85.
mol %, particularly preferably 60 to 83 mol %. In addition, the α-olefin components of the copolymer rubber include propylene, 1-butene, 4-methyl-1-
It is selected from pentene and the like, with propylene or 1-butene being particularly preferred. When a crystalline ethylene/α-olefin copolymer with an ethylene content of more than 85 mol% is used as a raw material,
The object of the present invention cannot be achieved because only a composition with inferior tack is obtained. Furthermore, in order to produce a composition with good holding power, it is not advantageous to use a copolymer rubber with a low ethylene content. In the present invention, the ethylene/α-olefin copolymer rubber graft-modified with an unsaturated carboxylic acid or a derivative thereof is used as the elastomer component. In the present invention, examples of the unsaturated carboxylic acid grafted to the ethylene/α-olefin copolymer rubber include acrylic acid, methacrylic acid, maleic acid, fumaric acid, and itaconic acid. Further, derivatives of unsaturated carboxylic acids refer to acid anhydrides, esters, amides, imides, metal salts, etc., such as maleic anhydride, citraconic anhydride, itaconic anhydride, methyl acrylate,
Methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, glycidyl acrylate, glycidyl methacrylate, monoethyl maleate, diethyl maleate, monoethyl fumarate, dimethyl fumarate, Itaconic acid monomethyl ester, itaconic acid diethyl ester, acrylamide, methacrylamide, maleic acid monoamide, maleic acid diamide, maleic acid-N-monoethylamide, maleic acid-N,N
-diethylamide, maleic acid-N-monobutylamide, maleic acid-N,N-dibutylamide,
Fumaric acid monoamide, fumaric acid diamide, fumaric acid-N-monoethylamide, fumaric acid-N,N-
Diethylamide, fumaric acid-N-monobutylamide, fumaric acid-N,N-dibutylamide, maleimide, N-butylmaleimide, N-phenylmaleimide, sodium acrylate, sodium methacrylate, potassium acrylate, potassium methacrylate, etc. can be mentioned. Among these, unsaturated dicarboxylic acids or their anhydrides are preferred because of their excellent properties.
Among them, it is most preferable to use maleic anhydride. Various known methods can be used to graft the above monomer onto the ethylene/α-olefin copolymer rubber. For example, it is carried out by heating the ethylene/α-olefin copolymer rubber and the graft monomer at high temperature in the presence or absence of a solvent, with or without the addition of a radical initiator. The amount of graft monomer grafted onto the ethylene/α-olefin copolymer rubber (hereinafter referred to as graft ratio) is 0.01 to 10.
It is preferable to adjust the amount by weight, particularly in the range of 1 to 5% by weight. Even if ethylene/α-olefin copolymer rubber is partially grafted,
There is no problem even if the whole part is grafted. In addition, when grafting a derivative of an unsaturated carboxylic acid, the derivative monomer may be directly grafted, or after grafting an unsaturated carboxylic acid or its acid anhydride, a part or all of the monomer may be grafted to an ester, amide, imide, metal. There is no problem even if it is modified into a derivative such as a salt. If the grafting rate is too low, tack and retention will be poor. On the other hand, if the grafting ratio is too high, the fluidity of the adhesive composition will be poor;
It becomes difficult to form a film. Examples of the tackifier that can be used in the present invention include aromatic, aliphatic, alicyclic, or copolymerized petroleum resins, terpene resins, rosin and its derivatives, coumaron/indene resins, etc. be able to. It is necessary that the melt index (hereinafter abbreviated as MI) of the modified ethylene/α-olefin copolymer rubber is from 0.01 to less than 5. If the MI is less than 0.01, the melt viscosity will be high and the adhesive coating performance will be poor. Also, those with MI of 5 or more have low melt viscosity;
When coating with an extrusion laminator or the like that is capable of high-speed coating, uneven coating tends to occur. The petroleum resin used in the present invention refers to a resin-like material obtained by polymerizing mixed unsaturated compounds that are by-produced during petroleum cracking or refining, and their hydrides. Ga-
Examples include resins obtained by polymerizing a fraction mainly consisting of aliphatic hydrocarbons with a boiling point range of 30 to +50°C and/or a fraction mainly consisting of aromatic hydrocarbons with a boiling point range of 100 to 300°C. Particularly preferred resin group petroleum resins have a softening point (ring and ball method) of about 70 to 130°C and a bromine number of about 20 to 130°C.
60, average molecular weight (vapor pressure method) is approximately 700 to 3000
Olefins and diolefins, mainly fractions with 4 and/or 5 carbon atoms containing unsaturated hydrocarbons, which are by-produced during petroleum refining or in the field, are processed using a Friedel-Crafts catalyst, usually at -15 to +100°C. It is obtained by polymerization. Moreover, an alicyclic hydrocarbon may be mixed in the unsaturated hydrocarbon. In addition, aromatic petroleum resins have a softening point (ring and ball method) of about 70 to 150°C and a bromine number of about 5 to 70.
It is obtained by polymerizing fractions containing vinyl aromatic compounds produced as by-products during petroleum refining or cracking using a Friedel-Crafts catalyst. Furthermore, aromatic petroleum resins are obtained by polymerizing polymers such as cyclopentadiene, dicyclopentadiene, coumaron, and indene, and fractions containing these, and have softening points of about 50 to 150°C and molecular weights of about 500 to 3000. , and resins with a bromine number of about 5 to 70. As the terpene resin, polymers or copolymers of terpenes such as pinene, terpinene, and limonene are used, but synthetic polyterpene resins equivalent to terpene resins obtained from materials similar to the raw materials for the petroleum resins can also be suitably used. . And the softening point is about
A terpene resin having a temperature of 70 to 130°C, a molecular weight of about 500 to 2000, and a bromine number of about 5 to 70 is used. Examples of rosin and its derivatives include natural rosin, rosin ester, and carboxylic acid-modified rosin. Among these tackifiers, terpene resins or aliphatic petroleum resins are preferred because they have excellent tackifying properties. In addition, to improve the heat-resistant hue and adhesive properties of hot-melt pressure-sensitive adhesives, resins obtained by graft-modifying petroleum resins (aromatic, copolymer, or aliphatic) or other resins with unsaturated carboxylic acids are also used. In the present invention, with respect to the total amount of the above-mentioned modified ethylene/α-olefin copolymer rubber and tackifier,
It is necessary to adjust the blending ratio of modified ethylene/α-olefin copolymer rubber to 30 to 70% by weight, preferably 40 to 60% by weight.
- If the blending amount of the olefin copolymer rubber exceeds the above range, the adhesive strength will decrease. The softeners used in the present invention to improve the flexibility and fluidity of the composition as necessary include paraffinic process oils made from high-boiling petroleum fractions, naphthenic process oils, aromatic process oils, Mineral oil softeners such as liquid paraffin, white oil and petrolatum, valuable oil softeners such as castor oil, cottonseed oil, linseed oil and rapeseed oil can be used. Among these, mineral oil-based softeners, particularly naphthenic process oils, are preferred because they have good compatibility with the elastomer component used in the present invention and the performance of the resulting adhesive is excellent. The blending amount of the softener should be limited to 50% by weight or less based on the total amount of the elastomer component and tackifier; if the blending amount is too large, the adhesive strength and holding power will be impaired. In addition to the above-mentioned components, the adhesive composition of the present invention can contain various compounding agents that are used in ordinary adhesives. For example, antioxidants such as phenolic compounds and sulfur-containing compounds, ultraviolet absorbers, fillers, and the like can be appropriately blended. The pressure-sensitive adhesive composition of the present invention can be prepared from the above-mentioned components by putting the components into a device such as a melting pot and melting and kneading them. Furthermore, in order to apply the pressure-sensitive adhesive composition of the present invention, the composition can be melted and then applied to a substrate by, for example, extrusion coating or extrusion lamination. By coextruding the material and the adhesive composition, an adhesive film or the like can be obtained. EXAMPLES Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples unless the gist thereof is exceeded. Example 1 [Method for preparing acrylic acid-modified ethylene/propylene copolymer rubber] Ethylene content 80 mol%, melt index
9.6 200g of ethylene-propylene copolymer rubber
- After charging xylene 1 into a reaction vessel, the atmosphere was replaced with nitrogen, and the temperature of the system was raised to 140°C to completely dissolve the copolymer rubber, followed by 24.5 g of acrylic acid and 1.35 g of dicumyl peroxide. g(p
-xylene solution) were added dropwise from separate supply ports over 4 hours each. Stirring was continued for an additional 2 hours to carry out the reaction. Thereafter, the mixture was cooled to room temperature, the reaction polymer was precipitated with acetone, and further washed to obtain a crumb-like purified modified ethylene-propylene copolymer rubber (hereinafter abbreviated as A-EPR). [Method for preparing adhesive and adhesive film] 100 parts by weight of A-EPR obtained by the above method, 100 parts by weight of terpene resin (product name: YS Resin p-1000, manufactured by Yasuhara Resin Co., Ltd.), naphthenic process oil (product name: San After putting 50 parts by weight of Oil 410 (manufactured by Sun Oil Co., Ltd.) and 2 parts by weight of an antioxidant (2.6-ditertiary-butyl-p-cresol) into a melting pot,
The mixture was kneaded at 150 to 170°C for 2 hours to prepare a pressure-sensitive adhesive composition. Next, the pressure-sensitive adhesive composition thus obtained was melted at 200°C using an extrusion laminator, and then applied to a biaxially stretched polyethylene terephthalate film with a film thickness of
Coated with 40 μm. [Method for evaluating adhesive properties] Tack: Performed by ball rolling method (J, DOW method). Adhesive strength: Performed by 180 degree peeling method (JIS Z 1523). Holding power: Adhesive tape with a load of 1 kg was attached to a JIS-specified stainless steel plate in an area of 15 x 25 mm width, and the displacement distance was measured after 2 hours. The results are shown in Table 1. Example 2 The acrylic acid in Example 1 was replaced with methacrylic acid,
The same procedure as in Example 1 was conducted except that methacrylic acid-modified ethylene-propylene copolymer rubber (hereinafter abbreviated as MTA-EPR) was used. The results are shown in Table 1. Example 3 The same procedure as in Example 1 was conducted except that acrylic acid in Example 1 was replaced with methyl methacrylate and methyl methacrylate modified ethylene-propylene copolymer rubber (hereinafter abbreviated as MMA-EPR) was used. Results first
Shown in the table. Example 4 Ethylene content 80 mol%, melt index
The procedure was repeated in the same manner as in Example 1, except that the ethylene-propylene copolymer rubber No. 9.6 was used as the raw material, kerosene was used as the solvent, the reaction temperature was 160°C, and the amount of maleic anhydride was 39.2 g instead of acrylic acid. A maleic anhydride-modified ethylene-propylene copolymer rubber (hereinafter abbreviated as MAH-EPR) having a unit content of 2.5% by weight and a melt index of 0.13 was obtained. Next, instead of A-EPR of Example 1, the above
An adhesive composition and an adhesive film were obtained in the same manner as in Example 1 except that MAH-EPR was used. As a result of measuring the adhesive properties of the coating film of this adhesive film, the tack was 7, the adhesive strength was 1520 (g/25 mm), and the holding power was 0.1 (mm/2 hours). Comparative Example 1 In Example 1, instead of MAH-EPR(1),
The same procedure as in Example 1 was conducted except that unmodified ethylene-propylene copolymer rubber (EPR-1) was used. The results are shown in Table 1.

[Table] Example 5, Comparative Example 2 MAH-EPR and SIS (trade name Kraton TR-
1107 (manufactured by Ciel Chemical) in the same manner as in Example 1 to obtain an adhesive film. Each of the obtained adhesive films was heated in an air oven at 230° C. for 6 hours, and then the adhesive properties of the coatings of the adhesive films were measured. The results are shown in Table 2.

【table】

Claims (1)

[Claims] 1 Ethylene/α-olefin modified copolymer rubber 30 with a melt index of 0.01 to less than 5, obtained by graft-modifying an ethylene/α-olefin copolymer with an ethylene content of 40 to 85 mol% with an unsaturated carboxylic acid or its derivative An adhesive film formed by coating a base material with an adhesive composition comprising 70 to 70% by weight and 70 to 30% by weight of a terpene resin or an alicyclic or aliphatic petroleum resin, or by laminating it with the base material. manufacturing method.