JPH103264A - Hot melt adhesive composition - Google Patents

Abstract

(57) Abstract: A hot-melt adhesive excellent in adhesiveness and hardly reduced in adhesiveness over time even when used to form a packaging material for packaging foods containing edible oils and the like. Providing a composition. SOLUTION: The composition contains 20 to 50% by weight of an ethylene-α-olefin copolymer having a density of 0.90 g / cm ³ or less, 5 to 70% by weight of a tackifier resin, and 5 to 45% by weight of a softener. A hot melt adhesive composition comprising:

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot-melt adhesive composition having excellent adhesive strength and little deterioration of the adhesive strength with time.

[0002]

2. Description of the Related Art A hot-melt adhesive composition has problems in that it exhibits fluidity by heating and melting, has a short set time, is solvent-free, and has no toxicity. There are advantages. And due to these advantages, bookbinding stiffening, cardboard and carton sealing,
In recent years, the amount of use has been increasing in various fields such as bag making, woodworking, shoemaking, and the like, and it has become extremely widespread especially in the field of paper sealing and packaging.

[0003] The above-mentioned packaging field includes the food packaging field and the like. In the food packaging field, hot-melt bonding using polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer or the like as a base resin is known. Agents are widely used. However, in a packaging pair formed using a hot melt adhesive having the base resin,
Soybean oil, sesame oil, cottonseed oil, rapeseed oil, olive oil, peanut oil, vegetable oils such as coconut oil, animal oils such as whale oil, tallow, lard, and modified products thereof, so-called edible oils (hereinafter simply edible oils) Oil)) and preserved and processed foods,
When packaging and storing food mixed with edible oil, there is a problem that the adhesive composition of the bag or the container or the sealing portion is eroded by the edible oil, causing cracks or reduced adhesiveness. Was.

[0004] Accordingly, an object of the present invention is to provide an excellent adhesive property,
It is still another object of the present invention to provide a hot-melt adhesive composition that exhibits a small decrease in adhesiveness over time even when used to form a packaging material for packaging foods and the like containing edible oil and the like.

[0005]

The present invention has a density of 0.9.
A hot melt adhesive containing 20 to 50% by weight of an ethylene-α-olefin copolymer of 0 g / cm ³ or less, 5 to 70% by weight of a tackifier resin, and 5 to 45% by weight of a softener. The above object has been achieved by providing a composition.

The present invention also provides the hot melt adhesive composition wherein the content of the tackifying resin is 15 to 50% by weight. Further, the present invention provides the hot melt adhesive composition, wherein the softener contains a process oil. Further, the present invention provides the above hot melt adhesive composition, wherein the softening agent contains paraffin wax having a melting point of 40 to 70 ° C. Further, the present invention provides the above-mentioned hot melt adhesive composition, wherein the above-mentioned adhesive composition is used for producing a packaging container for an edible oil-containing food.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the hot melt adhesive composition of the present invention will be described in more detail. The hot melt adhesive composition of the present invention contains a specific ethylene-α-olefin copolymer, a tackifying resin and a softener in specific contents.

The specific ethylene-α-olefin copolymer used in the present invention has a density of 0.9.
0 g / cm ³ or less, preferably 0.880 to 0.860
g / cm ³ of ethylene-α-olefin copolymer. When the density exceeds 0.90 g / cm ³ , the melt viscosity of the hot melt adhesive becomes too high. Here, the density is measured in the same manner as in the measurement of the density of a known polymer.

The ethylene-α-olefin copolymer is not particularly limited as long as it satisfies the above-mentioned density, but an ethylene-α-olefin copolymer obtained by copolymerization using a cyclopentadienyl complex as a catalyst may be used. Preferred are mentioned.

In the ethylene-α-olefin copolymer, the α-olefin to be copolymerized with ethylene is an α-olefin having 3 to 30 carbon atoms, for example, propylene, 1-butene, 1- Examples include pentene, 1-hexene, 1-octene, 1-heptene, 4-methylpentene-1, 4-methylhexene-1, 4,4-dimethylpentene-1, and octadecene. Among these, 1-hexene, 1-octene, 1-heptene, 4
-Methyl-pentene-1 is preferably used.

In the ethylene-α-olefin copolymer, the cyclopentadienyl complex used as a catalyst when ethylene and α-olefin are copolymerized is a compound represented by the following formula (I): And the like.

ML _X (I) wherein M is a transition metal selected from the group consisting of Zr, Ti, Hf, V, Nb, Ta and Cr, and L is
A ligand coordinated to the transition metal, a group having a cyclopentadienyl skeleton, a hydrocarbon group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, and an aryl group having 1 to 12 carbon atoms.
Roxy group, trialkylsilyl group having 1 to 12 carbon atoms, S
An O ₃ R group (R is a hydrocarbon group having 1 to 8 carbon atoms which may have a substituent such as halogen), a halogen atom or a hydrogen atom, and x is the same number as the valence of the above transition metal It is. However, when a plurality of Ls are coordinated, they may be different groups, but at least one is a group having a cyclopentadienyl skeleton. That is,
When x is 1, the L is a group having a cyclopentadienyl skeleton, and when x is 2 or more, at least one of the plurality of Ls has a cyclopentadienyl skeleton. Is a group having ]

Examples of the group having a cyclopentadienyl skeleton include a cyclopentadienyl group, a methylcyclopentadienyl group, a dimethylcyclopentadienyl group, a trimethylcyclopentadienyl group, and a tetramethylcyclopentadienyl group. Enyl group, pentamethylcyclopentadienyl group, ethylcyclopentadienyl group, methylethylcyclopentadienyl group, propylcyclopentadienyl group, methylpropylcyclopentadienyl group,
Alkyl-substituted cyclopentadienyl groups such as butylcyclopentadienyl group, methylbutylcyclopentadienyl group and hexylcyclopentadienyl group; or indenyl group, 4,5,6,7-tetrahydroindenyl group, fluorenyl And the like. Further, these groups may be substituted with a halogen atom, a trialkylsilyl group or the like.

As the above group having a cyclopentadienyl skeleton, an alkyl-substituted cyclopentadienyl group is particularly preferable among those exemplified above.

When the compound represented by the general formula (I) contains two or more groups having a cyclopentadienyl skeleton, two of the groups having a cyclopentadienyl skeleton are It may be bonded via an alkylene group such as ethylene or propylene; a substituted alkylene group such as isopropylidene or diphenylmethylene; or a substituted silylene group such as a silylene group or a dimethylsilylene group, a diphenylsilylene group or a methylphenylsilylene group.

Examples of the hydrocarbon group having 1 to 12 carbon atoms include an alkyl group, a cycloalkyl group, an aryl group and an aralkyl group. More specifically, the alkyl group includes a methyl group, Ethyl group, propyl group,
Examples of an isopropyl group and a butyl group include a cycloalkyl group such as a cyclopentyl group and a cyclohexyl group; examples of an aryl group include a phenyl group and a tolyl group; and examples of an aralkyl group include a benzyl group and a neophyl group. And the like. Examples of the alkoxy group include a methoxy group, an ethoxy group, and a butoxy group. Examples of the aryloxy group include a phenoxy group. Examples of the halogen atom include fluorine, chlorine, bromine, and iodine.

Examples of the SO ₃ R group include a p-toluenesulfonato group, a methanesulfonato group and a trifluoromethanesulfonato group.

The compound containing a group having a cyclopentadienyl skeleton, for example, when the valence of the transition metal is 4, is more specifically represented by the following formula (II).

R ² _k R ³ _l R ⁴ _m R ⁵ _n M (II) wherein M is the above-mentioned transition metal, and R ² is a group having a cyclopentadienyl skeleton (ligand ) And R ³ , R
⁴ and R ⁵ are a group having a cyclopentadienyl skeleton, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a trialkylsilyl group, an SO ₃ R group, a halogen atom or a hydrogen atom, respectively. And k is an integer of 1 or more, and k + 1 + m
+ N = 4. ]

In the present invention, in the above formula (II), R
Compounds in which at least two of R ² , R ³ , R ⁴ and R ⁵ , for example, R ² and R ³ are groups (ligands) having a cyclopentadienyl skeleton are preferably used. Groups having a skeleton (eg, R ² and R ³ ) may be linked as described above.

The following are specific examples of the above compounds wherein M is zirconium. Bis (indenyl) zirconium dichloride, bis (indenyl) zirconium dibromide, bis (indenyl) zirconium bis (p-toluenesulfonato) bis 4,5,6,7-
(Tetrahydroindenyl) zirconium dichloride, bis (fluorenyl) zirconium dichloride, ethylenebis (indenyl) zirconium dichloride, ethylenebis (indenyl) zirconium dibromide, ethylenebis (indenyl) dimethylzirconium, ethylenebis (indenyl) diphenylzirconium, ethylenebis ( (Indenyl) methylzirconium monochloride, ethylenebis (indenyl) zirconiumbis (methanesulfonato), ethylenebis (indenyl) zirconiumbis (p-toluenesulfonate), ethylenebis (indenyl) zirconiumbis (trifluoromethanesulfonate), ethylene Bis (4,5,6,7-tetrahydroindenyl) zirconium dichloride, isopropylidene (cyclopentane Enyl - fluorenyl) zirconium dichloride, isopropylidene (cyclopentadienyl - methylcyclopentadienyl) zirconium dichloride, dimethylsilylene bis (cyclopentadienyl)
Zirconium dichloride, dimethylsilylenebis (methylcyclopentadienyl) zirconium dichloride, dimethylsilylenebis (dimethylcyclopentadienyl)
Zirconium dichloride, dimethylsilylenebis (trimethylcyclopentadienyl) zirconium dichloride, dimethylsilylenebis (indenyl) zirconium dichloride, dimethylsilylenebis (indenyl) zirconiumbis (trifluoromethanesulfonato), dimethylsilylenebis (4,5,6,6) 7-tetrahydroindenyl) zirconium dichloride, dimethylsilylenebis (cyclopentadienyl-fluorenyl) zirconium dichloride, diphenylsilylenebis (indenyl)
Zirconium dichloride, methylphenylsilylenebis (indenyl) zirconium dichloride, bis (cyclopentadienyl) zirconium dichloride, bis (cyclopentadienyl) zirconium dibromide, bis (cyclopentadienyl) methylzirconium monochloride, bis (cyclopentane Dienyl) ethyl zirconium monochloride, bis (cyclopentadienyl) cyclohexyl zirconium monochloride, bis (cyclopentadienyl) phenyl zirconium monochloride, bis (cyclopentadienyl) benzyl zirconium monochloride, bis (cyclopentadienyl) ) Zirconium monochloride monohydride, bis (cyclopentadienyl) methylzirconium monohydride, bis (cyclopentadienyl) Methyl zirconium, bis (cyclopentadienyl) diphenyl zirconium, bis (cyclopentadienyl) dibenzyl zirconium, bis (cyclopentadienyl) zirconium methoxychloride, bis (cyclopentadienyl) zirconium ethoxycyclolide, bis (cyclopentane Dienyl) zirconium bis (methanesulfonato), bis (cyclopentadienyl) zirconium bis (p-toluenesulfonato), bis (cyclopentadienyl) zirconium bis (trifluoromethanesulfonato), bis (methylcyclopentadiene) Enyl) zirconium dichloride, bis (dimethylcyclopentadienyl) zirconium dichloride, bis (dimethylcyclopentadienyl) zirconium ethoxycyclolide, bis (dimethylcyclopen Dienyl) zirconium bis (trifluoromethanesulfonato), bis (ethylcyclopentadienyl) zirconium dichloride, bis (methylethylcyclopentadienyl) zirconium dichloride, bis (propylcyclopentadienyl) zirconium dichloride, bis (methylpropylcyclo) (Pentadienyl) zirconium dichloride, bis (butylcyclopentadienyl) zirconium dichloride, bis (methylbutylcyclopentadienyl) zirconium dichloride, bis (methylbutylcyclopentadienyl) zirconium bis (methanesulfonato), bis (trimethyl) Cyclopentadienyl) zirconium dichloride, bis (tetramethylcyclopentadienyl) zirconium dichloride, bis (pentamethylcyclopentadi Enyl) zirconium dichloride, bis (hexylcyclopentadienyl) zirconium dichloride, bis (trimethylsilylcyclopentadienyl)
Zirconium dichloride.

In the compounds exemplified above, disubstituted cyclopentadienyl rings such as dimethylcyclopentadienyl include 1,2- and 1,3-substituted compounds,
Trisubstituted compounds such as dimethylcyclopentadienyl are 1,2,2
Includes 3- and 1,2,4-substitutes. Also propyl,
Alkyl groups such as butyl are n-, i-, sec-, te
It includes isomers such as rt-. Examples of the compound also include a cyclopentadienyl complex in which zirconium is replaced with titanium, hafnium, vanadium, niobium, tantalum, or chromium in the above-mentioned compound in which M is zirconium.

The above cyclopentadienyl complex is
When used, they can be used alone or as a mixture. It may be used after being diluted with a hydrocarbon or a halogenated hydrocarbon. In particular, in the present invention, as the cyclopentadienyl complex, a zirconocene compound in which the central metal atom is zirconium and whose ligand is a group having at least two cyclopentadienyl skeletons is preferably used.

The above cyclopentadienyl complex is
It can be used in combination with an ordinary aluminoxane compound or a compound which reacts with the cyclopentadienyl complex to form a stable anion.

The cyclopentadienyl complex catalyst of the present invention is disclosed in JP-A-4-253711.
JP-A-4-279592, JP-T-6-50358
No. 5, JP-A-3-188092 or JP-A No.
A polymerization catalyst described in JP-A-84407 can also be used.

The mixing ratio of ethylene to α-olefin in the ethylene-α-olefin copolymer is preferably 40 to 98% by weight of ethylene and preferably 60 to 2% by weight of α-olefin.

The ethylene-α-olefin copolymer is prepared by converting ethylene and α-olefin in the presence of a cyclopentadienyl complex to 100 to 3,000 kg / c.
m ² , preferably 300 to 2,000 kg / cm ² ,
It can be produced by polymerizing at a temperature of 25 to 250 ° C, preferably 150 to 200 ° C by a high pressure ionic polymerization method. In particular, when the above-mentioned cyclopentadienyl complex and the above-mentioned aluminoxane compound are used in combination, polymerization is disclosed in
JP-A-1-130314, JP-A-60-35006,
According to the methods described in JP-A-58-19309, JP-A-60-35008, JP-A-3-1630088, etc., and the above cyclopentadienyl complex and a stable anion reacted with the cyclopentadienyl complex Can be used in combination with the compounds which form the carboxylic acids described in EP 277,004, WO 92/0172.
Polymerization can be carried out according to the high-pressure ionic polymerization method described in JP-A No. 3 (Kokai) No. 3 and the like.

The MFR of the ethylene-α-olefin copolymer (JIS K-7210; 190 ° C .;
(Measured under a load of 16 kg) is preferably 0.5 to 500 g
/ 10 minutes.

The above-mentioned ethylene-α-olefin copolymer has a permanent set of preferably 50% or less, more preferably 0 to 30%, and a hysteresis ratio of preferably 5.0 or less, more preferably 1 or less. It is desirably from 0.0 to 3.5. On the other hand, when the permanent set is 50% or the hysteresis ratio exceeds 5.0, the melt viscosity of the hot melt adhesive becomes too high, which is not preferable.

The permanent set and the hysteresis ratio are as follows:
Each is measured as follows. Measurement method of permanent strain: In the same manner as the measurement method of the hysteresis ratio described below, after elongating the sample by 100%, measure the length of the sample as the initial distance between chucks, and measure the initial length when elongating 100%. The ratio (%) of the non-relaxable length (length of the portion elongated and longer than the initial length) to the length (the initial distance between the chucks) was determined, and this was defined as the permanent strain. Hysteresis ratio measurement method; To examine the elasticity of each sample,
The hysteresis ratio was measured using an elongation tester with an integrating device. That is, a sample having a width of 25 mm was prepared using the elastic member, and the sample was placed on the tester with a distance between chucks of 100 m.
m and then each sample is 300 mm /
100% stretching at a speed of 10 min to form a stretching curve, and then loosening at the same speed to make the gap between the chucks equal to the initial length of 10%.
Relaxation was stopped at 0 mm to form a relaxation curve, the area under the stretching curve and the area under the relaxation curve were measured, and these were substituted into the following equation to calculate the hysteresis ratio. Hysteresis ratio = Area under stretch curve / Area under relaxation curve

As the above-mentioned ethylene-α-olefin copolymer, those obtained by copolymerization using a known metallocene catalyst can also be used.

The tackifying resin used in the present invention includes petroleum resin, hydrogenated petroleum resin, rosin, rosin derivative, tempen resin, cumarone-indene resin, low molecular weight polyamide styrene resin, and the like.
When used, they can be used alone or as a mixture. Among the resins exemplified above, the hydrogenated petroleum resin is particularly preferably used because it has no odor and is advantageous when the hot melt adhesive composition of the present invention is used for manufacturing food packaging containers. .

The softening agent used in the present invention is preferably a process oil, a paraffin wax having a melting point of 40 to 70 ° C. (preferably 50 to 60 ° C.). Can be used. That is, the softener preferably contains a process oil or a paraffin wax having the above melting point. Specific examples of the paraffin wax having the above melting point include a mixture of linear hydrocarbons having 16 to 49 carbon atoms, particularly 20 to 35 carbon atoms, and isoparaffins having 16 to 49 carbon atoms, particularly 20 to 35 carbon atoms. And those containing a small amount of cycloparaffin. When the melting point of the paraffin wax exceeds the above upper limit, the corrosion resistance of the resulting hot melt composition becomes insufficient, and when it is less than the above lower limit, the heat resistance may be insufficient. In the case of using paraffin wax, it is preferable to use paraffin wax having a melting point within the above range. In the present invention,
As the softener, a mixture of the above process oil and paraffin wax having a melting point within the above range can be preferably used. At this time, the mixing ratio of the process oil and the paraffin wax is not particularly limited and is arbitrary.In order to suppress the stickiness while lowering the melt viscosity of the obtained hot melt adhesive composition,
It is preferable to increase the mixing ratio of the paraffin wax, and to increase the stickiness while lowering the melt viscosity, it is preferable to increase the mixing ratio of the process oil. That is, by appropriately adjusting the mixing ratio of the process oil and the paraffin wax, it is possible to control the stickiness while lowering the melt viscosity.

The ethylene-α-olefin copolymer,
The specific content of the tackifying resin and the softening agent is such that the ethylene-α-olefin copolymer is 20%.
50 to 50% by weight, preferably 20 to 40% by weight, and the tackifier resin is 5 to 70% by weight, preferably 15 to 5% by weight.
0% by weight, and the softener is 5 to 45% by weight, preferably 25 to 45% by weight. When the content of the ethylene-α-olefin copolymer is less than 20% by weight,
The cohesive strength of the obtained hot-melt adhesive composition is reduced, and the adhesiveness is reduced. If it exceeds 50% by weight, the cohesive strength becomes too large, and the tack and adhesive strengths are reduced. Also,
The tackifier resin is considered to impart tackiness to the hot-melt adhesive composition at the time of melt application and to impart adhesive force to the surface of the adherend, and the content of the tackifier resin is 5% by weight. %, The effect is not exhibited, and if it exceeds 70% by weight, the cohesive region of the entire hot melt adhesive composition is reduced, and the adhesive strength is reduced. Furthermore, if the content of the paraffin wax is less than 5% by weight, the melt viscosity of the hot melt adhesive composition is not sufficiently reduced, so that the adhesive workability is deteriorated. If the content exceeds 45% by weight, the adhesive strength is reduced. I do.

The hot melt adhesive composition of the present invention may be composed of only the above-mentioned ethylene-α-olefin copolymer, the above-mentioned tackifying resin and the above-mentioned softening agent. Other components commonly used as the component (e.g., phenolic and amine-based antioxidants); and other components such as plasticizers and fillers such as calcium carbonate and titanium oxide can also be blended. When these other components are used, their content is preferably 5 to 55% by weight.

The hot-melt adhesive composition of the present invention is added to the above-mentioned components, and the mixture is molded into a linear or pellet form by a melt-stirring mixer or extruder, or kneaded by a kneader or the like to form a sheet or the like. Then, it can be used.

As described above, the hot melt adhesive composition of the present invention contains the ethylene-α-olefin copolymer, the tackifying resin, and the paraffin wax at specific contents, respectively. It is inexpensive, has excellent adhesive properties, and has excellent corrosion resistance. Therefore, the hot melt adhesive composition of the present invention is suitable as an adhesive for manufacturing packaging containers for foods such as foods having edible oil, bookbinding, cardboard manufacturing, diaper / napkin manufacturing, and the like. In particular, when hydrogenated petroleum resin is used as the tackifying resin, there is no odor, and in combination with edible oil resistance, food containers containing edible oil or food mixed with edible oil are used for packaging containers or storage. It is suitable as an adhesive for producing containers.

[0038]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

The methods for measuring each physical property in the examples are as follows. In Examples, unless otherwise specified, parts and% indicate parts by weight and% by weight, respectively. (1) Corrosion-resistant oil resistance: Two pieces of cardboard previously bent into a semicircular cross section are overlapped with one edge 5 mm on each side, and the adhesive composition is applied to the overlapped portion with a width of 10 mm. Applied. Further, the same treatment was applied to the other edge to obtain a cylindrical sample having a diameter of about 25 mm. This sample was placed on an insole of a desiccator containing soybean oil at the bottom, and left at 50 ° C. for 1 week. After standing for one week, the case where there was no abnormality in the film of the above-mentioned coated portion was evaluated as ○, and the case where cracks occurred was evaluated as ×. (2) Adhesive peel strength: aluminum foil of 40μ is adhered to each other by using the obtained composition, 20 ° C, and pulling speed 100m.
The 180 ° peel strength was measured under the condition of m / min, and this was defined as the bond peel strength. (3) Softening temperature: Measured according to JIS-K2531.

Examples 1 to 4 Ethylene-α-olefin copolymer (density 0.865 g / cm ³ , melt index 400 g / 10 min) shown in Table 1 and tackifying resin (hydrogenated petroleum resin, (Table 1)
Was added and melt-mixed to obtain a hot melt adhesive composition. The compositions and their properties are shown in [Table 1].

[0041]

[Table 1]

[0042]

The hot-melt adhesive composition of the present invention comprises:
The adhesiveness is excellent, and even when used to form a packaging material for packaging foods and the like containing edible oil and the like, the adhesiveness over time is less reduced.

Claims (5)

[Claims] 1. An ethylene-α-olefin copolymer having a density of 0.90 g / cm ³ or less, 20 to 50% by weight, a tackifier resin 5 to 70% by weight, and a softener 5 to 45% by weight. A hot melt adhesive composition comprising: 2. The content of the tackifying resin is from 15 to 5.
The hot melt adhesive composition according to claim 1, which is 0% by weight. 3. The hot melt adhesive composition according to claim 1, wherein the softener contains a process oil. 4. The hot melt adhesive composition according to claim 1, wherein the softener contains paraffin wax having a melting point of 40 to 70 ° C. 5. The hot melt adhesive composition according to claim 1, wherein the adhesive composition is for producing a packaging container for food containing edible oil.