JP7107313B2 - Emulsion and adhesive compositions containing copolymerized polyolefins - Google Patents

Description

TECHNICAL FIELD The present invention relates to an emulsion exhibiting good adhesion performance to olefinic resin substrates such as polyethylene and polypropylene.

Techniques for adhering substrates with low surface energy such as polyethylene and polypropylene have been studied for a long time, and it is known that it is not easy to design adhesives with high adhesion performance to these materials. As a technique for exhibiting good adhesion to these low surface energy substrates, a technology has been proposed in which the surface of the adherend is pretreated by corona discharge, plasma treatment, etc. to increase the surface energy before bonding. It is While these techniques are effective techniques, they require expensive equipment and increase power consumption.

On the other hand, products using olefin-based materials such as polyethylene and polypropylene have been increasing in recent years for various purposes ranging from everyday household goods to various industrial uses. Especially for in-vehicle applications, mounting of molding materials made of polypropylene is being actively pursued due to the trend toward weight reduction of automobiles. Under these circumstances, in recent years, more effective adhesives than ever before have been developed. In addition, recently, due to work environment problems, the conventional organic solvent-based adhesives are being changed to more environment-friendly water-based adhesives.

A tackifier is used for the above-mentioned adhesives for the purpose of imparting tackiness and improving adhesion. For example, Patent Document 1 describes an aqueous dispersion containing a polyolefin resin and a tackifier. It is

Patent No. 4033732

When a tackifier is used for the adhesive as described above, it is important to select a tackifier suitable for the substrate (adherend). However, in the above Patent Document 1, a tackifier that is dispersed in water by an emulsifier and a polyolefin resin aqueous dispersion are mixed, so a tackifier that is difficult to disperse in water cannot be used. Even when a water-dispersible tackifier is used, it may adversely affect the storage stability of the aqueous polyolefin resin dispersion depending on its interaction with the aqueous dispersion. In particular, olefin substrates such as polyethylene and polypropylene have low polarity and an extremely low SP value of around 8.0. Although it is necessary to use an imparting agent, it is difficult to mix such a tackifying agent with the polyolefin resin aqueous dispersion because of its poor hydrophilicity. Therefore, there has been a demand for an aqueous polyolefin resin dispersion that can be used with various tackifiers depending on the adherend.

The present invention provides an emulsion containing a polyolefin resin and a tackifier, which exhibits excellent storage stability regardless of the type of tackifier and exhibits good adhesion performance to olefin resin substrates such as polyethylene and polypropylene. and to provide an adhesive composition containing the emulsion.

In order to achieve the above object, the present inventors have made intensive studies and have proposed the following invention.

That is, the present invention is an emulsion containing a copolymerized polyolefin and a tackifier and satisfying the following (1) to (3).
(1) The copolymerized polyolefin is an ethylene-(meth)acrylic acid ester-maleic anhydride terpolymer (2) The copolymerized polyolefin is dispersed in water (3) Dispersion particles composed of the copolymerized polyolefin contains a tackifier

The 50% number average particle diameter of the tackifier-encapsulating copolymerized polyolefin dispersion particles preferably exceeds 100 nm.

The tackifier is preferably in the range of 5 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of the copolymerized polyolefin resin.

Any of the above emulsions can be used as an adhesive composition and an adhesive for polyolefin resins.

The emulsion of the present invention has good storage stability because the copolymerized polyolefin encapsulating the tackifier is uniformly and stably dispersed in water in the form of fine particles. Furthermore, since emulsions and adhesive compositions can be prepared regardless of the type of tackifier, the adhesiveness to substrates is excellent.

Embodiment of the Invention

Embodiments of the present invention will be described below.

<Copolymerized polyolefin>
The copolymerized polyolefin used in the present invention is a terpolymer containing ethylene, (meth)acrylic acid ester, and maleic anhydride as structural units. The copolymerized polyolefin may be any of random copolymers, block copolymers, and graft copolymers of ethylene, (meth)acrylic acid ester, and maleic anhydride, preferably random copolymers.

The content of the ethylene component is preferably 50% by mass or more and 95% by mass or less, more preferably 50% by mass when the total of the ethylene component, the (meth)acrylic acid ester component and the maleic anhydride component is 100% by mass. % by mass or more and less than 95% by mass, more preferably 60% by mass or more and 90% by mass or less, and particularly preferably 70% by mass or more and 80% by mass or less. When the content of the ethylene component is less than 50% by mass, the hydrophobicity of the copolymerized polyolefin is too low, and the adhesiveness to the olefin substrate may be reduced. When the content of the ethylene component is more than 95% by mass, the crystallinity of the copolymerized polyolefin becomes high, which may make water dispersion difficult.

Examples of (meth)acrylic acid esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, and 2-hydroxyethyl (meth)acrylate. mentioned. In addition, "(meth)acrylic acid" refers to "acrylic acid or methacrylic acid". When the total of the ethylene component, the (meth)acrylic acid ester component and the maleic anhydride component is 100% by mass, the content of the (meth)acrylic acid ester component is preferably 5% by mass or more and 49% by mass or less. , more preferably 10% by mass or more and 40% by mass or less, and still more preferably 15% by mass or more and 30% by mass or less. The most preferable range is 18% by mass or more and 29% by mass or less. If the content of the (meth)acrylic acid ester component is less than 5% by mass, the copolymerized polyolefin has a high melting point and may not be suitable for use as an olefin base material. If the content of the (meth)acrylic acid ester component is more than 49% by mass, the crystallinity of the copolymerized polyolefin may be remarkably reduced and the adhesiveness may be lowered.

When the total of the ethylene component, the (meth)acrylic acid ester component and the maleic anhydride component is 100% by mass, the content of the maleic anhydride component is preferably 0.01% by mass or more and 5% by mass or less, It is more preferably 0.1% by mass or more and 4% by mass or less, and still more preferably 1% by mass or more and 3% by mass or less. The most preferable range is 1.5% by mass or more and 2.5% by mass or less. If the content of the maleic anhydride component is less than 0.01% by mass, it may become difficult to disperse the copolymerized polyolefin in water. When the content of the maleic anhydride component is more than 5% by mass, the polarity of the copolymerized polyolefin increases, and the adhesion to low-polarity substrates such as olefins may decrease.

The melting point of the copolymerized polyolefin is preferably 50° C. or higher and 150° C. or lower, more preferably 55° C. or higher and 100° C. or lower, still more preferably 60° C. or higher and 90° C. or lower. If the melting point of the copolymerized polyolefin is lower than 50°C, the heat resistance when used as an adhesive may be poor. If the melting point of the copolymerized polyolefin is higher than 150°C, it may not be suitable for use as an olefin substrate.

The MFR (melt flow rate) of the copolymerized polyolefin at 190° C. and a load of 2160 g is preferably 0.1 g to 300 g/10 minutes, more preferably 1 g to 100 g/10 minutes, still more preferably 3 g to 30 g/10 minutes. is. If the MFR is less than 0.1 g/10 minutes, resin sagging or the like may occur when used as an adhesive. If the MFR is more than 300 g/10 minutes, the wettability to the substrate may be poor and the adhesiveness may be lowered.

The acid value of the copolymerized polyolefin is preferably 0.1 mgKOH/g or more and 56 mgKOH/g or less, more preferably 1 mgKOH/g or more and 45 mgKOH or less, and still more preferably 11 mgKOH/g or more and 34 mgKOH/g or less. The most preferable range is 16 mgKOH/g or more and 28 mgKOH/g or less. If the acid value is less than 0.1 mgKOH/g, it may become difficult to disperse the copolymerized polyolefin in water. If the acid value is more than 56 mgKOH/g, the polarity of the copolymerized polyolefin may increase and the adhesion to low-polarity substrates such as olefins may decrease.

<Tackifier>
The tackifier used in the present invention is not particularly limited, and rosin-based resins, terpene-based resins, coumarone resins, petroleum resins, etc. may be used depending on the substrate. The content of the tackifier is preferably 5 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of the copolymerized polyolefin. It is more preferably 10 parts by mass or more and 50 parts by mass or less, and still more preferably 20 parts by mass or more and 40 parts by mass or less. If the content of the tackifier is less than 5 parts by mass, the effect of the tackifier may not be obtained. If the content of the tackifier is more than 80 parts by mass, the dispersion particles of the copolymerized polyolefin may not contain the tackifier completely, resulting in an unstable emulsion.

The softening point of the tackifier is also not particularly limited, but from the viewpoint of adhesiveness and heat resistance, the softening point is preferably 60° C. or higher and 160° C. or lower, more preferably 70° C. or higher and 150° C. or lower, and further preferably 80° C. or higher and 145° C. or lower. 86° C. or higher and 140° C. or lower is most preferable. If the softening point of the tackifier is less than 60°C, the heat resistance when used as an adhesive may be insufficient. If the softening point of the tackifier exceeds 160°C, the wettability to the substrate may be poor and the adhesiveness may be lowered.

The SP value of the tackifier is also not particularly limited, and an appropriate tackifier may be selected according to the substrate. For example, for polyolefins such as polyethylene and polypropylene, the SP value of the tackifier is preferably 8.4 to 8.9 (J/cm ³ ) ^1/2 according to Hoy's formula. More preferably, it is 8.5 to 8.8 (J/cm ³ ) ^1/2 . It is known that the SP value (δ) of a polymer compound such as a tackifier according to Hoy's formula can be obtained as follows.
δ (polymer compound) = ρΣE/M
Here, ρ is the density of the polymer compound, M is the molecular weight of the repeating structural unit of the polymer compound, and E is the molar cohesive energy constant of the individual structural units constituting the polymer compound. As the numerical value of E, numerical values published in various documents can be used. References in which numerical values are described include, for example, J. Phys. Paint Technology vol. 42 76-118 (1970).

<Emulsion>
The emulsion of the present invention contains a copolymerized polyolefin and a tackifier, (1) the copolymerized polyolefin is an ethylene-(meth)acrylic acid ester-maleic anhydride terpolymer, and (2) the copolymerized polyolefin is dispersed in water, and (3) dispersion particles made of copolymerized polyolefin enclose a tackifier (hereinafter also referred to as tackifier-encapsulating copolymerized polyolefin dispersion particles).

The emulsion has good storage stability because dispersion particles made of a copolymerized polyolefin enclose a tackifier and are uniformly and stably dispersed in water in the form of fine particles. Furthermore, since emulsions and adhesive compositions can be prepared regardless of the type of tackifier, the adhesiveness to substrates is excellent.

In the emulsion of the present invention, the encapsulation state of the copolymerized polyolefin and the tackifier is such that the ethylene chain portion (hydrophobic portion) of the copolymerized polyolefin is inside and the carboxyl group portion (hydrophilic portion) derived from maleic anhydride is outside. The tackifier is included inside the copolymerized polyolefin as dispersion particles (micellar particles). Furthermore, it is believed that the hydrophilic sites of the copolymerized polyolefin are neutralized with a basic substance. This means that the tackifier, which by itself cannot be stably dispersed or dissolved in water and undergoes phase separation and sedimentation in water, does not undergo phase separation and sedimentation in the emulsion of the present invention and exists in a uniform and stable state. It can also be estimated from the fact that It can also be estimated from the fact that when the amount of the tackifier added increases, the particle size of the dispersion particles increases proportionally up to a certain amount.

The 50% number average particle size of the tackifier-encapsulating copolymerized polyolefin dispersion particles in the emulsion is preferably greater than 100 nm. If the particle size is 100 nm or less, there is a risk that the adhesiveness will deteriorate. Although the cause of the decrease in adhesiveness is not clear, when the particle size is 100 nm or less, the compatibility between the tackifier and the copolymerized polyolefin is extremely high, and when used as an adhesive, the tackifier wets the substrate interface. It is presumed that it does not spread. A more preferable particle size is 110 nm or more, and still more preferably 120 nm or more. Also, the upper limit of the particle size is preferably 500 nm or less. It is more preferably 400 nm or less, still more preferably 300 nm or less, and particularly preferably 200 nm or less. If the particle size is larger than 500 nm, the storage stability of the emulsion may deteriorate.

When preparing the emulsion of the present invention, it is preferable to use an emulsifier from the viewpoint of dispersion stability and storage stability. The emulsifier is not particularly limited, and examples thereof include anionic emulsifiers, cationic emulsifiers, nonionic emulsifiers (nonionic emulsifiers), amphoteric emulsifiers, and reactive emulsifiers. Among these, nonionic emulsifiers are particularly preferred. Also, the HLB of the nonionic emulsifier is preferably 10 or more. HLB is an index representing the balance between hydrophilicity and lipophilicity of an emulsifier (initial of Hydrophile-Lipophile Balance), and the higher the HLB value, the greater the hydrophilicity. When the HLB of the nonionic emulsifier to be used is less than 10, the lipophilicity of the emulsifier is too strong, so that the dispersion stability effect of the emulsion is small, and the dispersion stability may be worse than that of an emulsion containing no emulsifier. . The more preferred HLB of the nonionic emulsifier is 12 or higher, and the more preferred HLB is 16 or higher. Although the upper limit of HLB is not particularly limited, 19 or less is preferable.

The type of nonionic emulsifier is not particularly limited as long as it has an HLB of 10 or more. Alkylene styrenated phenyl ether type, polyoxyalkylene alkylphenyl ether type such as polyoxyethylene nonylphenyl ether, polyoxyalkylene alkylamine type such as polyoxyethylene stearylamine, polyoxyalkyleneamine such as polyoxyethylene polyoxypropylene monoamine type, polyoxyalkylene alkylamide type such as polyoxyethylene oleylamide, polyoxyalkylene fatty acid ester type such as polyoxyethylene monolaurate, polyoxyethylene polyoxypropylene glycol, polyoxyethylene polyoxypropylene tridecyl ether, etc. Examples include ethylene oxide propylene oxide block polymerization type, ethylene oxide propylene oxide random polymerization type, and polyoxyethylene sorbitan fatty acid esters such as polyoxyethylene sorbitan monostearate.

The emulsifiers may be used alone or in combination of two or more. Different types of emulsifiers such as an anionic emulsifier and a nonionic emulsifier may be combined, or the same type such as two nonionic emulsifiers may be combined. When nonionic emulsifiers are used in combination, it is preferable to use emulsifiers with different HLB.

The amount of the emulsifier to be added is preferably 1 part by mass or more and 25 parts by mass or less, more preferably 3 parts by mass or more and 15 parts by mass or less, and still more preferably 5 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the copolymerized polyolefin. is. If the amount of the emulsifier to be added is less than 1 part by mass, the dispersion stability and storage stability of the emulsion may deteriorate, and sedimentation of the copolymerized polyolefin may occur. If the amount of the emulsifier added is more than 25 parts by mass, the emulsifier may bleed out and the like, resulting in a decrease in adhesion to the substrate.

An example of the preparation method of the emulsion of the present invention is shown below, but the content is not limited to the following. That is, first, a copolymerized polyolefin and a tackifier are heated and dissolved in an ether solvent, an alcohol solvent, an aromatic solvent, and water in a predetermined ratio, and after adding an emulsifier, a basic substance is added and a medium is added. It can be obtained by removing the ether solvent, the alcohol solvent and the aromatic solvent after mixing and cooling.

This will be explained step by step.

First, a copolymerized polyolefin and a tackifier are heated and dissolved in an ether solvent, an alcohol solvent, an aromatic solvent and water in a predetermined ratio.

Examples of the ether-based solvent include, but are not limited to, tetrahydrofuran, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, and the like, and these may be used alone or in combination of two or more. can. Among them, tetrahydrofuran is preferred.

The alcohol-based solvent is not particularly limited, but includes aliphatic alcohols having 1 to 7 carbon atoms, aromatic alcohols, alicyclic alcohols, and the like, and these may be used alone or in combination of two or more. can. Examples of aliphatic alcohols having 1 to 7 carbon atoms include methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, pentanol and hexanol. Benzyl alcohol etc. are mentioned as aromatic alcohol. Cyclohexanemethanol etc. are mentioned as an alicyclic alcohol. Among them, aliphatic alcohols having 1 to 7 carbon atoms are preferred, aliphatic alcohols having 3 to 5 carbon atoms are more preferred, and isopropyl alcohol is even more preferred.

Examples of aromatic solvents include, but are not limited to, benzene, toluene, xylene, ethylbenzene, isopropylbenzene, solvent naphtha, and the like, and these can be used alone or in combination of two or more. Among them, toluene is preferred.

The ratio of the ether solvent, alcohol solvent and aromatic solvent to be used is not particularly limited, but the mass ratio is ether solvent:alcohol solvent:aromatic solvent=100:3 to 50:3 to 50. is preferably 100:5 to 35:5 to 35. If the ratio of the alcoholic solvent to 100 parts by weight of the etheric solvent exceeds 50 parts by mass, the solubility of the copolymerized polyolefin at high temperatures during the production process may decrease, and uniform dispersion may not be possible. On the other hand, when the proportion of the aromatic solvent exceeds 50 parts by mass, the particles aggregate to form a large amount of agglomerates, and uniform dispersion may not be possible. Moreover, if the ratio of the alcohol solvent or the aromatic solvent is less than 3 parts by mass, the effect may not be exhibited and uniform dispersion may not be possible.

Ratio of the total amount of copolymer polyolefin and tackifier, water, and the total organic solvent of ether solvent, alcohol solvent and aromatic solvent in the mixed system before heating and dissolving the copolymer polyolefin and tackifier. can be arbitrarily selected. 100-400:50-450 is more preferred. If the amount of water or total organic solvent is large, the dispersion of the copolymerized polyolefin in water will occur more easily, but the concentration will take time and the volumetric efficiency will decrease, which is economically disadvantageous and impractical. When there is little water, it is often impossible to disperse. If the total amount of the organic solvent is small, the viscosity will rise significantly during heating and dissolution, and uniform dissolution will not be possible, and as a result, uniform dispersion will not be possible.

Although the temperature for heating and dissolving is not particularly limited, it is preferably 50° C. or higher and 150° C. or lower. If the dissolution temperature is 50° C. or lower, the copolymerized polyolefin resin may not be sufficiently dissolved. If the temperature is 150°C or higher, it may exceed the lower pressure limit of the container. The dissolution time is also not particularly limited, but usually it can be completely dissolved in 1 to 2 hours.

The emulsifier can be added either before or after dissolving the copolymerized polyolefin and the tackifier. As described above, the emulsifier is not particularly limited, and anionic emulsifiers, cationic emulsifiers, nonionic emulsifiers (nonionic emulsifiers), amphoteric emulsifiers, reactive emulsifiers and the like can be used.

The basic substance may be blended either before or after dissolving the copolymerized polyolefin. Examples of basic substances include, but are not limited to, morpholine; ammonia; amines such as methylamine, ethylamine, dimethylamine, triethylamine, ethanolamine, and dimethylethanolamine. They can be used in combination. A preferred basic substance is dimethylethanolamine. The amount of the basic substance used is preferably 1 to 5 chemical equivalents, more preferably 1.5 to 3.5 chemical equivalents, relative to the carboxyl groups of the copolymerized polyolefin. If the amount is less than 1 equivalent, the carboxyl groups of the copolymerized polyolefin may not be sufficiently neutralized. If the amount exceeds 5 equivalents, the acid-base balance of the dispersion may be disturbed due to excessive basicity, resulting in an extremely high viscosity. As a method for adding the basic substance, it may be added as it is, or it may be added after being diluted with water for more uniform mixing. The time required for dispersion after addition of the basic substance is not particularly limited, but is preferably 1 to 2 hours.

Next, the organic solvent is removed from the obtained dispersion to obtain an emulsion. The organic solvent can be removed by distillation under reduced pressure. The degree of pressure reduction and the temperature during distillation are not particularly limited, but are preferably about 90 to 95 KPa (absolute pressure) and about 20 to 60°C. At this time, part of the water is also distilled off. The composition (mass ratio) of the emulsion after removing the organic solvent and part of the water by distillation under reduced pressure is copolymerized polyolefin: basic substance: water = 1: 0.06 to 0.33: 1.5 to 4. is preferred. The residual amount of the organic solvent after distillation under reduced pressure is preferably 1 part by mass or less, more preferably 0.1 part by mass or less, and 0 part by mass with respect to 100 parts by mass of the copolymerized polyolefin. is particularly preferred. Additional water can be added as needed.

The solid content concentration in the emulsion is preferably 10% by mass or more, more preferably 15% by mass or more, and still more preferably 20% by mass or more. Too little may not be practical. Also, it is preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less. If it is too large, the storage stability may deteriorate. The solids content in the emulsion refers to the total amount of copolymerized polyolefin, tackifier, emulsifier and basic substance.

<Adhesive composition>
The adhesive composition of the present invention is obtained by blending a curing agent with the above emulsion, if necessary. Examples of the curing agent include, but are not limited to, water-soluble polyfunctional epoxy resins, water-soluble polyfunctional carbodiimide resins, aqueous dispersions of polyfunctional isocyanate compounds, water-soluble silane coupling agents having polyfunctional silyl groups, and the like. . The curing agent preferably contains 0.8 to 1.2 equivalents of functional groups (the amount of epoxy groups, the amount of carbodiimide groups, the amount of isocyanate groups, or the amount of silyl groups) with respect to the acid value of the copolymerized polyolefin. More preferably, it is 0.9 to 1.1 equivalents. Among these, water-soluble polyfunctional epoxy resins are preferred. Specific examples of commercially available products manufactured by Nagase Chemtech Co., Ltd., "Denacol (registered trademark) EX-512", "Denacol EX-521", "Denacol EX-614B", "Denacol EX-821", "Denacol EX -920” and the like. These water-soluble epoxy resins can be added in any proportion to the emulsion of the present invention, but are preferably blended so that the epoxy group equivalent is equal to the acid value of the copolymerized polyolefin in the emulsion.

In addition, the emulsion of the present invention may contain various additives such as fillers, pigments, colorants, antioxidants, etc., as long as the effects of the present invention are not impaired. The content of the emulsion in the adhesive composition is preferably 60% by mass or more, more preferably 70% by mass or more, and still more preferably 80% by mass or more. Also, it is preferably 99% by mass or less, more preferably 95% by mass or less. By setting the amount within the above range, the excellent effect of the present invention can be exhibited.

Since the emulsion of the present invention has excellent adhesion to polyolefin resin substrates, it is useful as a primer for painting, printing, adhesion, and coating, as well as for paints, inks, coating agents, and adhesives.

The polyolefin-based resin substrate may be appropriately selected from conventionally known polyolefin resins. For example, although not particularly limited, polyethylene, polypropylene, ethylene-propylene copolymer, and the like can be used. Pigments and various additives may be added to the polyolefin resin base material, if necessary.

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these Examples. "Parts" in the examples and comparative examples indicate parts by mass. Moreover, the measurement/evaluation methods employed in the present invention are as follows.

1) Measurement of acid value of copolymerized polyolefin The acid value (mgKOH/g) in the present invention is the amount of KOH required to neutralize 1 g of copolymerized polyolefin, and is tested according to JIS K0070 (1992). It was measured according to the method. Specifically, after dissolving 1 g of polyolefin in 100 g of xylene adjusted to a temperature of 100° C., using phenolphthalein as an indicator at the same temperature, a 0.1 mol/L potassium hydroxide ethanol solution [trade name: 0.1 mol /L ethanolic potassium hydroxide solution", manufactured by Wako Pure Chemical Industries, Ltd.]. At this time, the amount of potassium hydroxide required for titration was converted to mg to calculate the acid value (mgKOH/g).

2) Measurement of Emulsion Solid Content Concentration About 1 g of sample emulsion is placed in a 50 ml glass weighing bottle and accurately weighed. Next, the weighing bottle containing the sample is dried in a hot air dryer at 120° C. for 2 hours, placed in a desiccator, left at room temperature for 30 minutes, and cooled. The weighing bottle is taken out from the desiccator, the mass is accurately weighed, and the weight % of the emulsion solid content concentration is calculated from the weight change (the following formula) before and after the hot air drying.
Emulsion solid content concentration (% by mass) = [(Sample mass before hot air drying) - (Sample mass after hot air drying)] / (Sample mass before hot air drying) x 100

3) Quantification of tackifier content The dry sample (resin) obtained by the measurement of the solid content concentration was dissolved in deuterated chloroform, and a nuclear magnetic resonance spectrometer (NMR) "Gemini-400-MR" manufactured by Varian was analyzed. Using ¹ H-NMR analysis, the ratio of the copolymerized polyolefin and the tackifier was determined.

4) Measurement of emulsion viscosity Using Toki Sangyo Co., Ltd. "Viscometer TV-22" (E-type viscometer), a 0.6 g sample was measured by rotor No. Measured under the conditions of 0.8° (=48′)×R24, range H, rotation speed 5 rpm, and 25°C.

5) Measurement of emulsion pH The value at 25°C was measured using "pH meter F-52" manufactured by Horiba. The calibration of the measuring instrument was made by Wako Pure Chemical Industries, Ltd., phthalate pH standard solution (pH: 4.01), neutral phosphate pH standard solution (pH: 6.86), borate pH standard A liquid (pH 9.18) was used, and three-point measurement was performed.

6) Measurement of 50% number average particle size of emulsion (copolymerized polyolefin dispersion particles containing tackifier) A sample prepared at a concentration of 0.05 g/L using "Zetasizer Nano Nano-ZS Model ZEN3600" manufactured by Malvern. was measured three times at 25°C, and the average value was taken.

7) Evaluation of Storage Stability of Emulsion The emulsions prepared in Examples and Comparative Examples were stored in incubators at 5° C., 25° C., and 40° C. in a stationary state, and changes in the appearance of the emulsion over time were observed. Observations were made after 1 week, 1 month, 3 months, 6 months and 12 months, and were scored as follows. 5 points: no change in appearance after 12 months, 4 points: no change in appearance after 6 months (resin condensation and sedimentation after that), 3 points: no change in appearance after 3 months (resin condensation and sedimentation after that) ), 2 points: no change in appearance after 1 month (resin condensation and sedimentation after that), 1 point: no change in appearance after 1 week (resin condensation and sedimentation after that), 0 points: after 1 week Aggregation and sedimentation of resin.

8) Evaluation of Adhesion to LDPE Substrate 0.5% by mass of Dynol (registered trademark) 604 (manufactured by Air Products Co., Ltd.) as a leveling agent was added to the emulsions obtained in Examples and Comparative Examples. The formulation was applied to a 0.1 mm thick low-density polyethylene (LDPE) film (Miporon Film, manufactured by Mitsuwa Co., Ltd.) using a #16E wire bar so that the thickness after drying was 6 μm. It was dried for 3 minutes in a hot air dryer at ℃. Remove from the dryer, place the same LDPE film on the coating film, and hold pressure for 30 seconds at 80 ° C. and holding pressure 0.3 MPa with a heat seal tester (manufactured by Tester Sangyo Co., Ltd., TP-701-B heat seal tester). A sample for LDPE adhesion strength measurement was molded. After standing overnight at room temperature, the sample for adhesive strength measurement was cut so that the width was 25 mm, and it was pulled up and down at a speed of 50 mm / min using Tensilon (RTG-1310, manufactured by A&D Co., Ltd.). The 180° peel adhesion strength was measured by pulling. The same test was performed 5 times, and the average value of the measured strength was taken as the LDPE adhesive strength.

9) Evaluation of Adhesion to HDPE Substrate 0.5% by mass of Dynol (registered trademark) 604 (manufactured by Air Products Co., Ltd.) as a leveling agent was added to the emulsions obtained in Examples and Comparative Examples. The formulation was applied to a high-density polyethylene (HDPE) test piece (2.0 x 25 x 100 mm, manufactured by Nippon Test Panel Co., Ltd.) using a #16E wire bar so that the thickness after drying was 6 μm. , and dried in a hot air dryer at 80°C for 3 minutes. Immediately after removing from the dryer, the same HDPE test piece was laminated to the coated surface so that the laminated part was 25 mm × 15 mm, and a load of 120 kg / m ² was applied and aged in an oven at 80 ° C. for 5 minutes to bond the HDPE. A sample for strength measurement was obtained. After leaving the adhesive strength measurement sample overnight at room temperature, tensile shear adhesive strength is measured by pulling up and down at a tensile speed of 50 mm / min using Tensilon (RTG-1310, manufactured by A&D Co., Ltd.). did. The same test was performed 5 times, and the average value of the measured strength was taken as the HDPE adhesive strength.

Tables 1 and 2 show the compositions of the copolymerized polyolefins and tackifiers used in the following examples and comparative examples.

Example 1
188 g of deionized water, copolymerized polyolefin manufactured by Japan Polyethylene Co., Ltd. (“Rekspearl (registered trademark) ET230X”; ethylene-(meth)acrylic acid ester-maleic anhydride terpolymer (mass ratio: 87.0-12) .0-1.0), MFR: 8.0 g / 10 minutes, melting point: 88 ° C., acid value: 11 mg KOH / g) 50 g, Yasuhara Chemical Co., Ltd. tackifier ("YS Polyster (registered trademark) T130"; terpene 7.5 g of phenol resin, softening point: 130° C.), 70 g of tetrahydrofuran, 5 g of isopropyl alcohol and 5 g of toluene were placed in an autoclave, heated to 120° C., and then heated and dissolved at the same temperature for 2 hours. Next, 5.0 g of an emulsifier (“DKS (registered trademark) NL-180”; polyoxyethylene lauryl ether, HLB: 16.1) manufactured by DAIICHI KOGYO CO., LTD. was added and dissolved by heating for another hour. Then, 2.5 g of dimethylethanolamine was added, dispersed for 1 hour, and then cooled to 40° C. (pre-emulsion). After that, the organic solvent/water was distilled off at a reduced pressure of 91 kPa (absolute pressure) to obtain a uniform emulsion (1) of pure white turbidity. The obtained emulsion (1) had a solid content concentration of 30.4% by mass, a viscosity at 25° C. of 12.3 mPa·s, a pH of 8.7, and a 50% number average particle size of 140 nm. In addition, it was confirmed by NMR that the content of the tackifier was 15 phr (15 parts by mass of the tackifier per 100 parts by mass of the copolymerized polyolefin), which was the same as the charged composition ratio. Emulsion (1) was stored in incubators at 5° C., 25° C., and 40° C., and storage stability was evaluated. No change in appearance was observed after 12 months. Further, using emulsion (1), the adhesion to LDPE substrate and the adhesion to HDPE substrate were evaluated according to the above procedure, and the results were 3.9 N/cm and 2.5 MPa, respectively.

Examples 2-12
Emulsions (2) to (12) were obtained in the same manner as in Example 1 according to the combinations shown in Table 3. The physical properties and adhesion of the emulsion were measured by the methods described above. Table 3 shows the composition and physical properties.

Comparative Example 1 below is an example in which an attempt was made to prepare an emulsion using an ethylene-(meth)acrylic acid ester copolymer, but a uniform and stable emulsion could not be obtained. Comparative Example 2 is an example in which an emulsion was prepared using an acid-modified polyolefin. Comparative Example 3 is an example in which the emulsion particles of the copolymerized polyolefin resin do not include the tackifier. Comparative Example 4 is an example of an emulsion containing a tackifier and not included in copolymerized polyolefin particles by adding a tackifier emulsion to the above emulsion not encapsulating a tackifier. Comparative Example 5 is an example in which an attempt was made to emulsify only the tackifier with an emulsifier, and no uniform and stable emulsion was obtained.

Comparative example 1
Instead of ethylene-(meth)acrylic ester-maleic anhydride terpolymer, copolymerized polyolefin resin (“Rexpearl A4250” manufactured by Japan Polyethylene Co., Ltd.; ethylene-(meth)acrylic ester copolymer (mass ratio: 75.0-25.0), MFR: 5.0 g/10 min, melting point: 92° C., acid value: 0 mg KOH/g) In the same manner as in Example 1 except that 50 g of the emulsion was used. An attempt was made to prepare (13), but a large amount of coarse particles were generated during cooling, and a uniform dispersion could not be obtained.

As a comparative example, an acid-modified polyolefin (A) was produced by the following method in order to use it instead of a copolymerized polyolefin. 750 g of a propylene-ethylene copolymer produced using a metallocene catalyst (propylene:ethylene = 93:7 molar ratio, melting point 75°C, melt viscosity at 180°C: 1500 mPa s) in a 3 L SUS autoclave reactor. , 90 g of maleic anhydride, 15 g of dicumyl peroxide, and 1,100 g of toluene were introduced and sealed. After purging the air in the autoclave with nitrogen, the mixture was heated and reacted at an internal temperature of 140° C. for 5 hours. The reaction solution was cooled to 110° C. and placed in a 10 L SUS container containing 3500 g of methyl ethyl ketone (MEK) to precipitate a resin, followed by solid-liquid separation to obtain a resin. The resin was further put into 1000 g of MEK, and the solid-liquid separation washing was repeated three times, and then the resin was dried to obtain an acid-modified polyolefin (A). The resulting acid-modified polyolefin (A) had a maleic anhydride content of 2.3% by mass and a weight average molecular weight of 34,000.

Comparative example 2
Emulsion (14) was prepared in the same manner as in Example 1 above, except that 50 g of the acid-modified polyolefin (A) was used instead of the ethylene-(meth)acrylate-maleic anhydride terpolymer. made. The physical properties and adhesion of the emulsion were measured by the methods described above. Table 4 shows the composition and physical properties.

Comparative example 3
Emulsion (15) was prepared in the same manner as in Example 1, except that the emulsion was prepared only from copolymerized polyolefin without using YS Polystar T130. The physical properties and adhesion of the emulsion were measured by the methods described above. Table 4 shows the composition and physical properties.

Comparative example 4
For 166 g (solid content: 50.1 g) of the above emulsion (15) (solid content: 30.2 wt%), a tackifier (“Harrier SK-385NS” manufactured by Harima Kasei Co., Ltd.; rosin emulsion, solid content: 50 mass %, softening point: 85° C.) (solid content: 7.5 g), 11 g of deionized water was added to adjust the solid content concentration, and the emulsion (16) was obtained by stirring at room temperature for 1 hour. Obtained. The physical properties and adhesion of the emulsion were measured by the methods described above. Table 4 shows the composition and physical properties.

Comparative Example 5 (Emulsifier dispersion of tackifier)
188 g of deionized water, 50 g of a tackifier manufactured by Yasuhara Chemical Co., Ltd. ("YS Polystar T130"; terpene phenol resin, softening point: 130°C), 70 g of tetrahydrofuran, 5 g of isopropyl alcohol and 5 g of toluene are placed in an autoclave and heated to 120°C. After that, it was heated and dissolved at the same temperature for 2 hours. Next, 5.0 g of an emulsifier manufactured by Daiichi Kogyo Co., Ltd. (“DKS NL-180”; polyoxyethylene lauryl ether, HLB: 16.1) was added, dissolved by heating for an additional hour, and then cooled to 40°C. . After that, the organic solvent/water was distilled off at a reduced pressure of 91 kPa (absolute pressure), but the tackifier precipitated during the distillation and a uniform emulsion was not obtained.

Comparative example 6
The emulsion (15) and the organic solvent/pre-emulsion prepared in Comparative Example 5 before distilling off the water were mixed so that the copolymer polyolefin: tackifier = 100: 15 (mass ratio), An emulsion containing an organic solvent was prepared, but the resin precipitated immediately.

The tackifiers used in Examples and Comparative Examples are as follows.
YS Polyster (registered trademark) T130: terpene phenolic resin, softening point: 130 ° C., manufactured by Yasuhara Chemical Co., Ltd. Alcon (registered trademark) P-90: aliphatic saturated hydrocarbon resin, softening point: 90 ° C., manufactured by Arakawa Chemical Industries, Ltd. Knit Resin (registered trademark) coumarone: coumarone resin, softening point 120 ° C., manufactured by Nikko Kagaku Co., Ltd. Harrier Star SK-385NS: rosin emulsion, softening point 85 ° C., manufactured by Harima Kasei Co., Ltd.

Since Examples 1 to 12 satisfy Claim 1, they exhibit high adhesiveness to both LDPE and HDPE, and are also excellent in storage stability. In Comparative Example 1, since no ethylene-(meth)acrylic acid ester-maleic anhydride terpolymer was used, a uniform dispersion could not be obtained. In Comparative Example 2, an acid-modified propylene-ethylene copolymer was used, and although the adhesiveness to HDPE was exhibited, the adhesiveness to LDPE was poor. Since Comparative Example 3 does not contain a tackifier, it has poor adhesion to LDPE and HDPE. Comparative Example 4 contains a tackifier, but is not encapsulated in the copolymerized polyolefin dispersion particles, resulting in poor storage stability. In Comparative Example 5, an attempt was made to emulsify the tackifier used in the Examples, but a uniform dispersion was not obtained. In Comparative Example 6, the copolymer polyolefin emulsion and the tackifier emulsion were simply mixed, and since the tackifier was not included in the copolymer polyolefin dispersion particles, the resin precipitated and no emulsion was obtained. .

Since the emulsion of the present invention has excellent adhesion to polyolefin resin substrates, it is useful as a primer for painting, printing, adhesion, and coating, as well as for paints, inks, coating agents, and adhesives.

Claims (5)

An emulsion containing a copolymerized polyolefin and a tackifier ,
(1) the copolymerized polyolefin is an ethylene-(meth)acrylic acid ester-maleic anhydride terpolymer ,
(2) the copolymerized polyolefin is dispersed in water ,
(3) The dispersion particles made of a copolymerized polyolefin enclose a tackifier, and the 50% number average particle diameter of the tackifier-encapsulated copolymerized polyolefin dispersion particles is more than 100 nm and 500 nm or less.
emulsion. The emulsion according to claim 1, wherein the tackifier is in the range of 5 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of the copolymerized polyolefin resin. An adhesive composition containing the emulsion according to claim 1 or 2 . 4. The adhesive composition according to claim 3 , which is an adhesive for polyolefin resins. A copolymer polyolefin, which is a terpolymer containing ethylene, (meth)acrylic acid ester and maleic anhydride as structural units, and a tackifier are dissolved in a solvent and water, and after adding a basic substance, the solvent is A method for producing an emulsion that removes