JP4553624B2 - Aqueous dispersion and laminate - Google Patents

Description

  The present invention relates to an aqueous dispersion of an ethylene / (meth) acrylic acid copolymer excellent in dispersibility and film-forming property, and a laminate obtained by applying it to a substrate. In particular, the present invention relates to an aqueous dispersion useful as a heat seal material for a packaging material or a rust preventive paint for a metal material.

  Conventionally, aqueous dispersions of various polymers have been applied in order to impart heat sealing performance to a base film or for the purpose of rust prevention of metal materials. For example, an acrylic or EVA aqueous dispersion may be used to form a heat seal layer on a base film, but an aqueous dispersion such as a surfactant is used when preparing the aqueous dispersion. There was a problem that the water dispersant remained in the coating film after being applied to the material film. In order to avoid such problems, an aqueous dispersion in which ethylene / (meth) acrylic acid copolymer is dispersed in water with a base is widely used. However, depending on the application, further improvement in heat seal strength is required. It was done. For example, when a sealant layer is formed by applying to a biaxially oriented polypropylene film (OPP film), further improvement in heat seal strength has been required depending on the field of use. Further, when such an aqueous dispersion of ethylene / (meth) acrylic acid copolymer is used as a rust preventive paint for a metal material, a rust preventive paint having further excellent moisture resistance has been demanded.

  The present invention has been made to satisfy the above-mentioned requirements, and the object thereof is excellent in dispersibility and film-forming property, and when applied to a base film such as an OPP film, the heat seal strength. It is an object to provide an aqueous dispersion capable of forming a large sealing layer. Another object of the present invention is to provide an aqueous dispersion capable of forming a rust-preventing layer having excellent moisture resistance when applied to a metal material.

That is, the present invention provides an ethylene / (meth) acrylic acid copolymer (A) having a (meth) acrylic acid content of 5 to 30% by weight, and 5 to 500 parts by weight based on 100 parts by weight of the copolymer (A). Rosin or its derivative (B) having an acid value of 100 to 700 mg KOH / g and water, and the copolymer (A) is based on the carboxyl group of the copolymer (A) And an aqueous dispersion dispersed in water with 40 to 500 mol% of a lower aliphatic amine . The present invention also relates to a laminate obtained by applying and drying such an aqueous dispersion on a substrate such as a thermoplastic resin, a metal material, or glass.

  ADVANTAGE OF THE INVENTION According to this invention, the aqueous dispersion excellent in the dispersibility and film forming property can be provided. Since such an aqueous dispersion has improved wettability with respect to a hydrophobic polymer such as an OPP film, it is possible to obtain good coating properties, and the kind of rosin or its derivative (B). And by appropriately selecting the blending amount, it is possible to form a seal layer exhibiting excellent heat seal strength when applied to a substrate, particularly an OPP film. The aqueous dispersion also has good coating properties for metal materials, and by appropriately selecting the type and blending amount of rosin or its derivative (B), rust prevention excellent in moisture resistance performance A layer can be formed. Furthermore, even when applied to glass, a coating film can be formed with high adhesive strength.

  As a raw material of the aqueous dispersion of the present invention, an ethylene / (meth) acrylic acid copolymer having a (meth) acrylic acid content of 5 to 30% by weight, preferably 10 to 25% by weight, more preferably 15 to 25% by weight. (A) is used. When a copolymer having a (meth) acrylic acid content less than the above range is used, it is difficult to obtain a stable aqueous dispersion. On the other hand, when a copolymer having a content exceeding 30% by weight is used. Although it is temporarily dispersed, it immediately aggregates and it is difficult to obtain an aqueous dispersion having excellent storage stability. In the present invention, (meth) acrylic acid means acrylic acid or methacrylic acid.

  Such a copolymer may also be obtained by copolymerizing other monomers in addition to ethylene and (meth) acrylic acid. Examples of such other monomers include vinyl acetate, methyl acrylate, ethyl acrylate, isobutyl acrylate, n-butyl acrylate, unsaturated esters such as methyl methacrylate, and carbon monoxide. Can do. Such other monomers may be contained, for example, in a proportion of 20% by weight or less, preferably 10% by weight or less.

  As the ethylene / (meth) acrylic acid copolymer, two or more kinds of copolymers having different kinds of acid, (meth) acrylic acid content and / or melt flow rate can be used. Two or more kinds of ethylene / (meth) acrylic acid copolymers having different (meth) acrylic acid contents are used so that the average (meth) acrylic acid content is 10 to 30% by weight, particularly 15 to 25% by weight. And an aqueous dispersion with a reduced viscosity compared to an aqueous dispersion using one ethylene / (meth) acrylic acid copolymer having the same (meth) acrylic acid content as the average (meth) acrylic acid content The body can be obtained, and therefore the solid content concentration can be increased. In particular, an ethylene / (meth) acrylic acid copolymer having a (meth) acrylic acid content of 8 to 15% by weight and an ethylene / (meth) acrylic acid copolymer having a (meth) acrylic acid content of 15 to 30% by weight. The coalescence is preferably used in such a proportion that the average (meth) acrylic acid content falls within the above range. In this case, the difference between the former and latter (meth) acrylic acid contents is preferably 1% by weight or more, particularly preferably 3 to 10% by weight.

  As the raw material ethylene / (meth) acrylic acid copolymer, considering the ease of production of the aqueous dispersion, the dispersion stability, the physical properties of the coating film obtained from the aqueous dispersion, JIS K7210-1999, 190 ° C. A melt flow rate at a load of 2160 g is preferably 1 to 2000 g / 10 min, particularly 10 to 1000 g / 10 min.

  In the present invention, together with the ethylene / (meth) acrylic acid copolymer, rosin or a derivative thereof having an acid value of 100 to 700 mgKOH / g, preferably 150 to 500 mgKOH / g is used. Examples of such high acid value rosins include rosin, hydrogenated rosin, polymerized rosin, and acid-modified rosin. By using a rosin having an acid value in the above range or a derivative thereof, an aqueous dispersion having good water dispersibility can be obtained, and such an aqueous dispersion is applied to a hydrophobic polymer such as an OPP film. In this case, wettability can be improved, coating properties can be improved, and a seal layer having high heat seal strength can be formed. Moreover, when apply | coating to a metal material, the antirust coating film which is excellent in moisture-proof performance can be formed. As rosin or a derivative thereof, it is preferable to use a rosin having a ring-and-ball method softening point of about 70 to 150 ° C., particularly about 75 to 140 ° C., depending on the purpose of use of the aqueous dispersion.

  The aqueous dispersion of the present invention comprises the above-mentioned ethylene / (meth) acrylic acid copolymer (A) or the ethylene / (meth) acrylic acid copolymer (A) and rosin or its derivative (B) as a lower aliphatic group. It is formed by dispersing in water using a base such as amine, alkali metal compound or alkali metal ion, alkaline earth metal compound or alkaline earth metal ion. Although depending on the purpose of use of the aqueous dispersion, rosin or its derivative (B) is used in an amount of 5 to 500 parts by weight, preferably 10 to 10 parts by weight based on 100 parts by weight of the ethylene / (meth) acrylic acid copolymer (A). Used at a ratio of 400 parts by weight.

In the present invention, the term “lower aliphatic amine” is used to include ammonia, and preferably has the general formula R _m NH _3−m (wherein R is a C _n H _{2n + 1} group or HO— C _k H _2k -group, wherein n is 1, 2, 3 or 4, k is 1, 2 or 3, m is 0, 1, 2 or 3). More specifically, ammonia, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, mono-n-propylamine, di-n-propylamine, tri-n-propylamine, monoisopropylamine, diisopropylamine, triisopropyl Lower aliphatic monoamines such as amine, monoethanolamine, diethanolamine, and triethanolamine can be exemplified as representative examples. Of these, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine and the like are particularly preferable.

  Examples of the alkali metal in the alkali metal compound or alkali metal ion include lithium, sodium, potassium, cesium, and rubidium, and sodium or potassium is particularly preferable. Examples of the alkaline earth metal in the alkaline earth metal compound or alkaline earth metal ion include calcium, magnesium, and barium.

  The lower aliphatic amine, alkali metal compound or alkali metal ion, or alkaline earth metal compound or alkaline earth metal ion is 40 to 500 mol% based on the carboxyl group of the ethylene / (meth) acrylic acid copolymer (A). The ratio is preferably 50 to 300 mol%. When the above alkaline earth metal compound or alkaline earth metal ion is used, it is preferably used in combination with a lower aliphatic amine, an alkali metal compound or an alkali metal ion. In addition, a compound or ion of a polyvalent metal such as zinc can be used in combination as long as the water dispersibility is not significantly impaired. In the above, in order to obtain a coating film excellent in moisture resistance and water resistance, it is preferable to use a lower aliphatic amine such as ammonia.

  The aqueous dispersion of the present invention can be produced by the following method. That is, water and the ethylene / (meth) acrylic acid copolymer (A) and rosin or its derivative (B) having the above-mentioned properties in an amount of 5 to 50% by weight, preferably 10 to 40% by weight. A shear force between a lower aliphatic amine, an alkali metal compound or an alkaline earth metal compound having an ion amount as described above based on the carboxyl group of the copolymer, and optionally a polyvalent metal compound. Can be obtained by reaction while applying a shearing force at a temperature of 100 ° C. or higher, preferably 130 to 200 ° C. in a reaction apparatus capable of applying a pressure, for example, an autoclave equipped with a stirrer. The reaction time varies depending on the reaction temperature and other reaction conditions, but is about 30 to 300 minutes. Examples of the alkali metal compound include hydroxides, carbonates, hydrogen carbonates, carboxylates and the like. As the alkaline earth metal compound or other polyvalent metal compound, use of an oxide, hydroxide, carbonate or the like is preferable.

  In the present invention, in addition to the above-described method, the alkali metal ionomer or alkaline earth metal ionomer of the ethylene / (meth) acrylic acid copolymer (A) prepared in advance and rosin or its derivative (B) and necessary Accordingly, the aqueous dispersion of the present invention can be produced by a method in which other alkali metal or alkaline earth metal compound is dispersed in water while applying a shearing force.

  The aqueous dispersion of the present invention prepared as described above has an average particle size of 1 to 5000 nm, particularly 5 to 3000 nm, and Brookfield viscosity in consideration of dispersion stability, coatability, coating film uniformity, and the like. It is preferable that the viscosity at 23 ° C. measured by the meter is 1 to 10000 mPa · s, particularly 5 to 5000 mPa · s, and the pH is 8 to 12, preferably 8.5 to 11.5.

  Various additives can be arbitrarily blended in the aqueous dispersion of the present invention. Examples of such additives include antioxidants, UV absorbers, light stabilizers, antistatic agents, plasticizers, pigments, dyes, lubricants, antiblocking agents, adhesives, crosslinking agents, foaming agents, viscosity modifiers. Agents, surfactants, writability improvers, inorganic fillers and the like.

  The aqueous dispersion of the present invention can be applied to various substrates and dried for various purposes such as imparting heat sealing performance and forming a rust-preventive coating film to obtain a laminate having these performances. Can do. Base materials include high, medium and low density polyethylene, ethylene / α-olefin copolymer, ethylene / vinyl acetate copolymer, ethylene / (meth) acrylic acid ester copolymer, ethylene / (meth) acrylic acid copolymer. Polymer or its ionomer, ethylene / (meth) acrylic acid / (meth) acrylic acid ester copolymer or its ionomer, olefin polymer such as polypropylene, poly-1-butene, poly-4-methyl-1-pentene Or copolymer, polystyrene, high impact polystyrene, ABS type resin, styrene resin such as styrene / butadiene block copolymer or hydrogenated product thereof, polyethylene terephthalate, polyester such as polybutylene terephthalate, nylon 6, nylon 66 Like polyamide, polycarbonate , Thermoplastic polymers such as polyvinyl chloride and mixtures of these in any proportion, rubber materials such as natural rubber, synthetic rubber, thermosetting resins such as phenolic resin, polyurethane, iron, copper, aluminum, stainless steel, etc. Examples thereof include natural materials such as metal, glass, ceramics, wood, paper, rayon and leather. The thermoplastic polymer can be applied to various molded products such as films, sheets, hollow molded products, injection molded products, woven fabrics, nonwoven fabrics, and synthetic leathers. By using a flat substrate such as a film, sheet, woven fabric, nonwoven fabric, synthetic leather, or paper as the substrate, a laminate in which a heat seal layer is formed on the substrate can be easily obtained. The aqueous dispersion of the present invention is excellent in wettability not only with polar materials but also with hydrophobic materials such as olefin polymers and styrene polymers, so that the aqueous dispersion has good coatability. The body can be applied. For example, a film obtained by applying and drying the aqueous dispersion of the present invention on a polyolefin film, typically an OPP film, exhibits good heat seal performance and can be suitably used as various packaging materials. In addition, the laminate obtained by applying the aqueous dispersion of the present invention to a metal material and drying is excellent in rust resistance, in particular moisture and rust resistance, and should be used suitably for applications requiring rust prevention. Can do. Furthermore, the laminate obtained by applying and drying the aqueous dispersion of the present invention on glass has excellent coating film adhesion, and can be used in the fields of adhesives for glass, inks for glass, and the like.

  The aqueous dispersion of the present invention can be modified with other polymer dispersions, or can be blended with other polymer dispersions at an arbitrary ratio for the purpose of modifying other polymer dispersions. In general, it is preferably blended at a ratio of 10/90 to 90/10, particularly 20/80 to 80/20 in terms of solid content (weight ratio).

  Such other polymer aqueous dispersions are those having a pH of 7 or more, or those having a pH of 7 or more with aqueous ammonia, etc., and do not gel when mixed with the aqueous dispersion of the present invention. It is necessary to choose something like this. Further, it is desirable to select those having a solid content concentration of 2 to 60%, preferably about 5 to 50%, and an average particle size of 1 to 10000 nm, preferably 5 to 5000 nm.

  Such other polymer aqueous dispersions include, for example, polyvinyl acetate, ethylene / vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, water-soluble acrylic resin, acrylamide resin, methacrylamide resin, acrylonitrile resin, Methacrylonitrile resin, styrene, acrylic acid copolymer, water-soluble polyurethane resin, water-soluble styrene / maleic acid copolymer, styrene / butadiene copolymer, high impact polystyrene resin, polybutadiene resin, polyester resin, acrylonitrile / butadiene copolymer Polymer, polyethylene, polyethylene oxide, propylene / ethylene copolymer, maleic anhydride grafted polyolefin, chlorinated polyethylene, chlorinated polypropylene, EPDM, phenol resin, silicone resin, epoxy resin It can be mentioned aqueous dispersion. Of course, two or more of these may be used.

  In order to apply the aqueous dispersion of the present invention to a substrate, a known method, for example, a coating method such as roll coating, reverse roll coater, doctor coater, brush coating, spray coating, screen printing, gravure printing, engraving roll printing, Printing methods such as flexographic printing can be adopted. The base material may be coated with a primer for the purpose of improving adhesiveness or the like, or may be subjected to a surface treatment such as corona treatment. Although the thickness of a dry coating film is arbitrary, what is necessary is just to apply | coat so that thickness may become 1-300 micrometers, Preferably it is 5-200 micrometers, and this may be dried.

  EXAMPLES Next, although an Example demonstrates this invention in detail, this invention is not restrained by these Examples. In addition, the raw material used for the Example and the physical-property evaluation method of an aqueous dispersion are shown below.

[Aqueous dispersion material]
(1) Base polymer BP-1: ethylene / acrylic acid copolymer (acrylic acid content 20% by weight, melt flow rate (MFR) 300 g / 10 min)
BP-2: ethylene / methacrylic acid copolymer (methacrylic acid content 20% by weight, MFR 300 g / 10 min)
(2) Ion source dimethylamine aqueous solution: concentration 40% by weight (manufactured by Kanto Chemical Co., Inc.)
(3) Rosin Rn-1: Rosin (Arakawa Chemical Co., Ltd. KR612, acid value 160-175 mgKOH / g, ring and ball method softening point 80 ° C.)
Rn-2: Rosin (Arakawa Chemical Co., Ltd. KR604, acid value 230-245 mgKOH / g, ring and ball method softening point 132 ° C.)

[Method for evaluating properties of aqueous dispersion]
(1) pH
Measured using pH METER F-12 manufactured by Horiba, Ltd.
(2) Viscosity The viscosity was measured at 23 ° C. using a Brookfield viscometer. Unit (mPa · s)
(3) Particle size It measured using LB-500 by Horiba, Ltd. The median diameter was taken as the particle size. Unit (nm)

(4) Moisture-resistant adhesion evaluation method (a) With a target of 4 μm for coating thickness, The aqueous dispersion is applied to the electrolytic galvanized steel sheet with a 4-bar coater and dried at 100 ° C. for 2 minutes.
(B) Hold in a constant temperature and humidity chamber at a temperature of 50 ° C. and a humidity of 90% for 24 hours.
(C) Lightly apply filter paper to remove moisture from the coating surface and hold for 2 hours.
(D) Use a cutter knife to make a 15 mm gap and a width of 40 mm.
(E) A cellophane adhesive tape is applied, pressed firmly with an eraser, and the adhesive tape is attached to the coated surface.
(F) After holding for about 1 minute, peel off quickly and measure the residual rate (%) of the coating film.

(6) Heat seal performance (HS performance) evaluation: Unit (g / 15mm)
(A) Between OPP and OPP A 50 μm-thick OPP film subjected to corona treatment was subjected to No. 1 aqueous dispersion with a target thickness of 10 μm. It was applied using an 18 bar coater and dried at 100 ° C. for 3 minutes. Two obtained OPP films were overlapped so that the coated surfaces were in contact with each other, heat sealed under conditions of a temperature of 140 ° C., a pressure of 2 kg / cm ² , and a sealing time of 0.5 seconds, and then the heat seal strength was measured. .
(B) OPP-Glass Corona-treated OPP film having a thickness of 50 μm, an aqueous dispersion having a target thickness of 10 μm. It was applied using an 18 bar coater and dried at 100 ° C. for 3 minutes. The obtained OPP film was superposed so that the coated surface was in contact with a glass plate having a thickness of 4 mm, and heat-sealed under conditions of a temperature of 140 ° C., a pressure of 2 kg / cm ² , and a sealing time of 0.5 seconds. The heat seal strength was measured.

[Example 1]
72 g of base polymer (BP-1), 8 g of rosin (Rn-1), 309 g of ion-exchanged water and 18.8 g of dimethylamine aqueous solution were added to the autoclave and stirred for 1.5 hours at a temperature of 150 ° C. and a stirring speed of 1200 rpm. Thereafter, it was cooled with tap water to obtain an aqueous dispersion 1 having a solid concentration of 20% by weight.

[Example 2]
56 g of base polymer (BP-1), 24 g of rosin (Rn-1), 309 g of ion-exchanged water, and 18.8 g of aqueous dimethylamine solution were added to the autoclave and stirred for 1.5 hours at a temperature of 150 ° C. and a stirring speed of 1200 rpm. Thereafter, the mixture was cooled with tap water to obtain an aqueous dispersion 2 having a solid concentration of 20% by weight.

[Example 3]
40 g of base polymer (BP-1), 40 g of rosin (Rn-1), 309 g of ion-exchanged water, and 18.8 g of aqueous dimethylamine solution were added to the autoclave and stirred for 1.5 hours at a temperature of 150 ° C. and a stirring speed of 1200 rpm. Thereafter, the mixture was cooled with tap water to obtain an aqueous dispersion 3 having a solid content concentration of 20% by weight.

[Example 4]
40 g of base polymer (BP-1), 40 g of rosin (Rn-1), 311 g of ion-exchanged water and 15.0 g of dimethylamine aqueous solution were added to the autoclave, and the mixture was stirred at a temperature of 150 ° C. and a stirring speed of 1200 rpm for 1.5 hours. Thereafter, it was cooled with tap water to obtain an aqueous dispersion 4 having a solid concentration of 20% by weight.

[Example 5]
24 g of base polymer (BP-1), 56 g of rosin (Rn-1), 311 g of ion-exchanged water, and 15.0 g of a dimethylamine aqueous solution were added to the autoclave and stirred for 1.5 hours at a temperature of 150 ° C. and a stirring speed of 1200 rpm. Thereafter, the mixture was cooled with tap water to obtain an aqueous dispersion 5 having a solid concentration of 20% by weight.

[Example 6]
72 g of base polymer (BP-1), 8 g of rosin (Rn-2), 309 g of ion-exchanged water, and 18.8 g of aqueous dimethylamine solution were added to the autoclave and stirred for 1.5 hours at a temperature of 150 ° C. and a stirring speed of 1200 rpm. Thereafter, the mixture was cooled with tap water to obtain an aqueous dispersion 6 having a solid concentration of 20% by weight.

[Example 7]
56 g of base polymer (BP-1), 24 g of rosin (Rn-2), 309 g of ion-exchanged water, and 18.8 g of aqueous dimethylamine solution were added to the autoclave and stirred for 1.5 hours at a temperature of 150 ° C. and a stirring speed of 1200 rpm. Thereafter, the mixture was cooled with tap water to obtain an aqueous dispersion 7 having a solid concentration of 20% by weight.

[Example 8]
72 g of base polymer (BP-2), 8 g of rosin (Rn-1), 311 g of ion exchange water, and 15.7 g of dimethylamine aqueous solution were added to the autoclave, and the mixture was stirred for 1.5 hours at a temperature of 150 ° C. and a stirring speed of 1200 rpm. Thereafter, the mixture was cooled with tap water to obtain an aqueous dispersion 8 having a solid concentration of 20% by weight.

[Comparative Example 1]
80 g of base polymer (BP-1), 309 g of ion exchange water, and 18.8 g of aqueous dimethylamine solution were added to the autoclave, and the mixture was stirred for 1.5 hours at a temperature of 150 ° C. and a stirring speed of 1200 rpm. Thereafter, the mixture was cooled with tap water to obtain an aqueous dispersion 9 having a solid concentration of 20% by weight.

[Comparative Example 2]
80 g of base polymer (BP-2), 311 g of ion-exchanged water, and 15.7 g of dimethylamine aqueous solution were added to the autoclave, and the mixture was stirred for 1.5 hours at a temperature of 150 ° C. and a stirring speed of 1200 rpm. Thereafter, the mixture was cooled with tap water to obtain an aqueous dispersion 10 having a solid concentration of 20% by weight.

  Table 1 shows the results of measuring the ratio of the raw materials used in the aqueous dispersions 1 to 10 and the physical properties of the aqueous dispersion.

＊：透明性不良につき、測定不能

*: Cannot be measured due to poor transparency

Claims (7)

An ethylene / (meth) acrylic acid copolymer (A) having a (meth) acrylic acid content of 5 to 30% by weight and an acid value of 5 to 500 parts by weight per 100 parts by weight of the copolymer (A) Contains 100 to 700 mg KOH / g rosin or its derivative (B) and water, and the copolymer (A) is 40 to 500 based on the carboxyl group of the copolymer (A). An aqueous dispersion comprising a mol% lower aliphatic amine dispersed in water. 2. The aqueous dispersion according to claim 1 , wherein the melt flow rate (JIS K6760, 190 ° C., 2160 g load) of the ethylene / (meth) acrylic acid copolymer (A) is 5 to 1500 g / 10 minutes. The ethylene / (meth) acrylic acid copolymer (A) comprises two or more ethylene / (meth) acrylic acid copolymer mixed components, and the average (meth) acrylic acid content is 10 to 30% by weight. Item 3. The aqueous dispersion according to Item 1 or 2. Two or more kinds of ethylene / (meth) acrylic acid copolymer mixed components are ethylene / (meth) acrylic acid copolymer and (meth) acrylic acid having a (meth) acrylic acid content of 8 wt% or more and less than 15 wt%. The aqueous dispersion according to claim 3 , which is a mixed component of an ethylene / (meth) acrylic acid copolymer having a content of 15 to 30% by weight. Lower aliphatic amine has the general formula _{R m NH 3-m} (wherein, R _C n _{H 2n + 1} - group or _{HO-C k H 2k} - group, where n is 1, 2, 3 or 4, k is 1 The aqueous dispersion according to any one of claims 1 to 4, wherein 2 or 3, m is represented by 0, 1, 2 or 3). The laminated body formed by apply | coating and drying the aqueous dispersion in any one of Claims 1-5 to a base material. The laminate according to claim 6 , wherein the substrate is a thermoplastic resin, metal, or glass.