JPS643236B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an adhesion method using a hot melt adhesive composition containing an ethylene copolymer as a main component, and particularly to an adhesion method using a composition with improved physical properties at low temperatures. Conventionally, the most commonly used hot melt adhesives are those with a base polymer of ethylene-vinyl acetate copolymer, which is combined with a tackifying resin, wax, and, if necessary, an anti-aging agent. It is a compound containing additives, antioxidants, fillers, colorants, softeners, etc., and is made into an adhesive by mixing these by hot melting. As the base polymer, an ethylene copolymer such as ethylene-pinyl acetate copolymer or ethylene-ethyl acrylate copolymer is used. Tackifying resins include rosin, hydrogenated rosin, partially hydrogenated rosin, rosins such as various rosin esters, terpene resins such as α- or β-pinene or dipentene polymers, aromatic or aliphatic. petroleum-based hydrocarbon resins, or their hydrides, coumaron indene resins, terpene phenol resins, and equivalent substances. The wax may be paraffin wax obtained from fractional distillation of petroleum, microcrystalline wax, low molecular weight polyethylene, amorphous polypropylene, or a low molecular weight copolymer of ethylene and propylene. Known softeners include naphthenic mineral oil, polybutene, chlorinated paraffin, chlorinated biphenyl (PCB), chlorinated triphenyl, dioctyl phthalate, and tricresyl phosphate. Adhesives, fillers, if necessary for these materials
Add anti-aging agents, colorants, etc. and mix to create wood, paper,
Immediately after applying (i.e., before cooling and solidifying) adherends such as cloth, cellophane, plastic, metal, etc., using a hot melt applicator, for example.
It is used by adhering or by applying it on an adherend in advance, cooling it, and then heat-sealing and adhering it to another adherend using an iron, heat press, hot roll, high frequency, etc. Further, specific fields in which such hot melt adhesives are used include various fields such as perfect binding of books and sealing of packaging boxes. Furthermore, in recent years, various types of packaged foods and the like have increasingly been stored at low temperatures, and as a result, hot melt adhesives used in food packaging boxes and the like have come to be required to have low-temperature properties. However, conventional adhesives become brittle at low temperatures, causing cracks in the adhesive layer, and the adhesive strength itself is not sufficient at low temperatures, and no hot melt adhesive with satisfactory low-temperature properties has yet been obtained. Furthermore, in order to improve the low-temperature properties of hot melt adhesives, rather than modifying the base polymer, tackifying resin, wax, etc., or using new materials, it is necessary to improve the low-temperature properties by adding a softener. is the easiest. However, a softening agent that sufficiently improves low-temperature properties and satisfies heat resistance and other properties has not yet been obtained. In other words, as a softening agent
Toxicity is a problem when using PCBs and phthalate esters, and chlorinated paraffin easily decomposes and becomes colored and generates toxic gas when heated.
Mineral oil, polybutene, etc. have poor compatibility with other components and cannot provide sufficient low-temperature properties. Other softeners may not have sufficient compatibility with each component, may have poor heat resistance, weather resistance, etc., may not have satisfactory low-temperature properties, or may not provide sufficient adhesive strength. The present invention relates to an adhesion method using a hot melt adhesive composition that improves the low temperature properties that are disadvantageous in the past and at the same time has sufficient adhesive strength and heat resistance. It is characterized by consisting of the components () to (). That is, () Base polymer consists of a copolymerized component of ethylene and 15 to 45% by weight of one or more fatty acid vinyl esters, and has a melt index (MI) of 0.1 to 45% by weight.
100 parts by weight of 1000 ethylene copolymer, () 30 to 200 parts by weight of tackifying resin, () 10 to 200 parts by weight of wax, and () (softening agent) one or more diarylalkane.
parts by weight, and one or two alkyl-3-phenylindane derivatives represented by the following general formula (A)
The mixture contains 0.01 to 9 parts by weight of the species or more in an amount of 1 to 50 parts by weight. general formula In the above formula, R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are hydrogen atoms or methyl groups, and the total carbon number of R ₁ to R ₅ is 1 to 3. In the base polymer of the present invention, the monocarboxylic acid vinyl ester to be copolymerized with ethylene is typically a fatty acid vinyl ester such as vinyl acetate. Furthermore, a copolymer of a small amount of acrylic acid or methacrylic acid can also be used as the third component. The content of components to be copolymerized with ethylene is 15-45% by weight in the copolymer.
If it is less than 15%, sufficient adhesive strength cannot be obtained,
When it exceeds 45%, the cohesive force is lost and both are unsuitable as adhesives. Further, a more preferable range of the copolymer component is 20 to 40% by weight.
MI is set in the range of 0.1 to 1000, preferably 1 to 500, taking into account fluidity during melt application with an applicator. In addition, MI is expressed as the number of grams flowing out in 10 minutes at 190°C and a load of 2160gr according to ASTM D-1238. Note that these copolymers can be easily obtained by known methods, for example, the polymerization methods described in US Pat. Nos. 2,200,429 and 2,703,794. Since the above-mentioned copolymer itself has poor adhesive properties, it is used with the addition of a tackifying resin. The tackifying resin in the composition of the present invention includes rosin, polymerized rosin, hydrogenated rosin, partially hydrogenated rosin, or rosins such as glycerin or pentaerythritol ester thereof, and terpenes such as α-pinene, β-pinene, and dipentene. or terpene resins such as copolymers with styrene, terpene modified products such as terpene phenol resins, aliphatic hydrocarbon resins, aromatic hydrocarbon resins, and combinations of aromatics and aliphatics. polymerized hydrocarbon resin,
Petroleum resins represented by cyclopentadiene resins, their hydrides, coumaron indene resins,
and other known tackifying resins may be used. Tackifying resins used in hot melt adhesives are required to have heat resistance in addition to adhesive strength and low-temperature properties, so hydrogenated rosins, partially hydrogenated rosins or their esters, terpene resins, styrene and isobutylene Copolymerized hydrocarbon resins, hydrogenated petroleum resins, and the like are preferred as they provide good properties. Furthermore, among aromatic petroleum resins, we have reduced the conjugated diolefin content and indene content of aromatic petroleum resins with good thermal stability, such as fractions with a boiling point range of 140 to 220°C obtained by thermal decomposition of petroleum. Aromatic petroleum resin with excellent hue and heat resistance obtained by adjusting the concentration and Friedel-Crafts polymerization (US Patent No. 3778421)
(1) of claim 1 of No. 1) is preferable as it provides excellent performance. Adding a tackifying resin improves adhesive strength, but
If the amount added is too large, the adhesive strength will decrease and the low-temperature properties will deteriorate, so 30 parts by weight of the copolymer as the base polymer
It is appropriate to use ~200 parts by weight, and this amount is preferably from 40 to 150 parts by weight. The combination of the copolymer and tackifying resin has a high melt viscosity and is difficult to apply with an applicator, so wax is used to adjust the viscosity. The wax used in the present invention includes paraffin wax and microcrystalline wax,
It also includes low molecular weight polyethylene, amorphous polypropylene, and copolymers of low molecular weight propylene and ethylene. Parafin wax is a solid hydrocarbon obtained during the fractional distillation of petroleum, and its melting point is usually about 37.7-65.5℃ (about 100℃).
〓～150〓) is a virtually colorless hard substance.
Like paraffin wax, microcrystalline wax is obtained by distilling petroleum, but unlike paraffin wax, it contains high molecular weight hydrocarbons with side chains and usually has a melting point of about 68.3~
The temperature is 93.3℃ (approximately 155-200℃). Low molecular weight polyethylene is preferably polyethylene with an average molecular weight of 300 to 10,000, amorphous polypropylene is preferably one with an average molecular weight of 1,000 to 200,000, and crystalline polypropylene (isotactic polypropylene)
It is also possible to use lumps that are by-produced during the production of. A copolymer of low molecular weight propylene and ethylene can also be used. Wax is added mainly to adjust the melt viscosity, but wax itself does not have adhesive properties, and the adhesive strength decreases as the amount added increases. It is appropriate to use 10 to 200 parts by weight, more preferably 10 to 100 parts by weight. In the present invention, 1 to 50 parts by weight of a mixture consisting of a diarylalkane and an alkyl-3-phenylindane derivative represented by the general formula (A) above is used as a softener. Among the diarylalkane, preferred compounds are diarylethanes, and more preferred are arylphenylethanes represented by the following general formula (B). general formula In the above formula, R ₁ to R ₃ are a hydrogen atom or a C ₁ to _{C 3} alkyl group, and the total number of carbon atoms in R ₁ to R ₃ is 3 or less. Specific examples of diarylalkanes include 1,1
-Diphenylethane, 1,1-di(methylphenyl)ethane, 1-phenyl-1-(methylphenyl)ethane, 1-phenyl-1-(dimethylphenyl)ethane, 1-phenyl-1-(ethylphenyl)ethane, 1- Phenyl-1-(methylethylphenyl)ethane, 1-phenyl-1-(isopropylphenyl)ethane, 1-phenyl-1-
Examples include (trimethylphenyl)ethane. These can be easily produced by reacting styrene or alkylstyrene with alkylbenzene in the presence of a Lewis acid catalyst. It can also be obtained by separating it from by-product oil during the production of ethylbenzene. These diarylalkane may be used alone or as a mixture of two or more. The alkyl-3-phenylindane derivative of the general formula (A) can be obtained by dimerizing styrene or its alkyl derivative with an acidic catalyst such as a solid acid catalyst. Among the alkyl-3-phenylindane derivatives, preferred compounds are those obtained by cyclic dimerization of styrene, α-methylstyrene, or vinyltoluene, such as 1-methyl-3-
Phenylindane, 3-methyl-3-phenylindane, 1,1,3-trimethyl-3-phenylindane, 1-methyl-3-phenylindane,
-Methyl-3-phenyl-methylindane, etc., and -methyl-3-phenylindane is particularly preferred. Diarylalkane itself has excellent compatibility with ethylene copolymers such as ethylene-vinyl acetate copolymer (EVA), but when used in combination with alkyl-3-phenylindane derivatives, the compatibility is further improved and adhesive properties are improved. Since the properties are improved and the heat resistance is also improved, it becomes a suitable softener for hot melt adhesives. Furthermore, although it cannot be said that the alkyl-3-phenylindane derivative itself necessarily improves the fluidity of the obtained composition, the melt viscosity of the hot melt adhesive composition can be improved by using diarylalkane in combination. It can be adjusted to a preferred range. The mixing ratio of diarylalkane and alkyl-3-phenylindane derivative is arbitrary, but the former is 1 to the latter 0.01 to 9 (weight ratio),
Preferable from the viewpoint of synergistic effects. The purpose of adding a softener to the hot melt composition of the present invention is, of course, to improve the low-temperature properties, but the addition of the softener improves wetting to adherends and improves the low-temperature properties and adhesive strength. However, if too much softener is blended, the heat resistance will decrease, so the amount of softener added is 1 to 50 parts by weight, preferably 5 to 50 parts by weight, based on 100 parts by weight of the copolymer as the base polymer. It is 30 parts by weight. Moreover, a small amount of other known softeners can also be used in combination. The composition of the present invention may contain other additives such as anti-aging agents, antioxidants,
Calcium carbonate, clay, zinc oxide, silicate,
Fillers such as carbon black, coloring agents, etc. can be added. The components of the hot melt adhesive composition of the present invention can be melt-mixed by a known method, for example in a kneader at 130-250°C, preferably 150-200°C.
It can be heated and melted and mixed at ℃. If the heating temperature is too high, it causes deterioration, decomposition, and coloration of each component, while if it is too low, the melting is insufficient or the viscosity is too high, which is inconvenient for mixing. Further, an appropriate hot melt adhesive applicator can be used for this composition, but in this case, the operating temperature is 130 to 250°C, preferably 150 to 200°C, and the melt viscosity of the composition is 100,000 to 100,000°C. It is used at less than centipoise, preferably less than 10,000 centipoise. The hot melt adhesive composition of the present invention can be used for various adherends. In particular, metal foil, paper,
It is an effective adhesive for bonding a variety of adherends including cardboard, wax-coated paper, and polymeric films such as polyethylene and polypropylene films. In the present invention, the composition prepared using the above-mentioned softener has excellent aging resistance and weather resistance, so it can withstand long-term storage and use without discoloration or deterioration of adhesive performance. Furthermore, since the softener itself has excellent compatibility with each component to be blended, no phase separation occurs, and no leaching or migration of the softener is observed. Furthermore, since the softener used in the present invention is not soluble in water, the composition according to the present invention provides an adhesive with excellent water resistance. Adhesives using the composition of the present invention have improved low-temperature properties and excellent adhesive strength and heat resistance, which are extremely satisfactory characteristics from a practical standpoint. The invention will be explained in further detail in the following examples. Examples and Comparative Examples (1) Formulations Five types of hot melt adhesive compositions were prepared according to the following formulations. () Base polymer...100 parts by weight (vinyl acetate content 28% by weight, EVA with melt index 150, trade name Evaflex #220,
(manufactured by Mitsui Polychemical Co., Ltd.) () Tackifying resin...100 parts by weight (aromatic petroleum resin, trade name: Neopolymer S,
(manufactured by Nippon Petrochemical Co., Ltd.) () Wax...50 parts by weight (paraffin wax with a melting point of 62.7℃ (145〓),
(manufactured by Nippon Oil Co., Ltd.) () Softener...5 parts by weight (each shown in Table 1 was used)

【table】

[Table] (2) Compounding method Melt and mix the ethylene-vinyl acetate copolymer and wax while stirring in a container with a stirrer, then add the softener and tackifying resin in that order and melt and mix again to form the adhesive. A drug composition was obtained. The melting temperature is
The desired adhesive composition was easily obtained at 150 to 180°C and for a mixing time of 1 to 2 hours. (3) Preparation of test piece The obtained adhesive composition was pressed to a thickness of 2 mm.
It was made into a sheet and used as a test piece for low-temperature property tests. In addition, the test pieces for adhesion tests and heat resistance tests are
By pressing at 180° C. for 3 minutes, the thickness of the adhesive layer was adjusted to 220 μm, and aluminum foil was adhered to the adhesive layer, which was then used for each test. (4) Test method Low temperature property test: A 2 mm thick test piece was bent at -5°C along mandrels with diameters of 2 mmφ and 6 mmφ to test low temperature properties. If the test piece did not break when bent, it was marked with a circle, and the test piece was judged to have good low-temperature properties. If it was broken, it was indicated by an x mark, and on the other hand, the low-temperature properties were determined to be poor. Adhesion test: A test piece made by adhering aluminum foil to each other using a press was cut into 25 mm width, and tested using an Instron type tensile tester at room temperature (20°C) and -5°C.
A T-peel test was carried out at a tensile speed of 300 mm/min.
Adhesive strength was expressed as the load (g/25 mm) required for peeling. Heat resistance test: A load of 100 g was applied to a test piece with an adhesive area of 20 mm x 20 mm obtained in the same manner as the adhesive strength test.
The test piece was hung vertically and the deviation (mm) after 1 hour at 55°C was displayed. In addition, if the deviation was large and there was a fall, it was indicated as a fall. In this test,
The smaller the deviation, the better the heat resistance of the adhesive. (5) Test results The above test results are shown in Table 2.

[Table] As can be seen from the test results in Table 2, the hot melt adhesive composition of the present invention has better low-temperature properties, as well as superior adhesive strength and heat resistance, compared to the adhesive composition of the comparative example. .

Claims (1)

[Claims] 1 () Consisting of a copolymerized component of ethylene and 15 to 45% by weight of one or more fatty acid vinyl esters, and having a melt index of
100 parts by weight of 0.1-1000 ethylene copolymer, () 30-200 parts by weight of tackifying resin, () 10-200 parts by weight of wax, and () 1 part by weight of one or more diarylalkane, and one of the alkyl-3-phenylindane derivatives represented by the following general formula (A)
An adhesion method in which a hot melt adhesive composition consisting of 1 to 50 parts by weight of a mixture of 0.01 to 9 parts by weight of one or more species is melted by heating and adhered while being cooled and solidified; In the above formula, R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are hydrogen atoms or methyl groups, and the total carbon number of R ₁ to R ₅ is 1 to 3. 2. The bonding method according to claim 1, wherein the diarylalkane is arylphenylethane. 3 The alkyl-3-phenylindane derivative is 1-methyl-3-phenylindane or 3-
The bonding method according to claim 1 or 2, wherein methyl-3-phenylindane is used.