JP2008095044A - Resin composition for sealing material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat-sealing resin composition which is suitable as a heat-sealing material used for plastic containers, especially for impact-resistant polystyrene containers, has peel strengths from container main body-forming materials in a more suitable range than those of conventional materials, holds various physical properties required as the heat-sealing materials, such as container content-sealing protecting properties, for foods, or the like, approximately equivalently to conventional materials, and exhibits higher heat resistance than those of conventional materials and smooth and comfortable peel touch on peeling, even when heat-treated at a low temperature. <P>SOLUTION: This heat-sealing resin composition for the heat-sealing material comprises 30 to 80 pts.mass of an ethylene-vinyl ester copolymer resin (A), 1 to 45 pts.mass of ethylene-(meth)acrylate copolymer resin (B), and 3 to 30 pts.mass of a tackifying resin (C) [the total amount of (A), (B) and (C) is 100 pts.mass]. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a resin composition for a sealing material, and more specifically, a specific blending ratio of an ethylene / vinyl ester copolymer resin, an ethylene / (meth) acrylate copolymer resin and a tackifier resin. The present invention relates to a resin composition for a sealing material, which is made of a resin composition and is suitably used for sealing a plastic container, in particular, an impact-resistant polystyrene container and a lid.

Plastic containers with easy-open lids are widely used as various foods and pharmaceutical containers such as jelly, pudding, yogurt, tofu, instant men and noodles.
In particular, container materials such as instant men in cups, noodles, and soup powders are widely made of foamed polystyrene sheets or those with impact-resistant polystyrene films bonded to them, impact-resistant polystyrene sheets, polyethylene laminated paper, etc. It is used.
Various heat sealing materials have been proposed and put to practical use for sealing and sealing these plastic containers in an easy-open form with lids. Among them, ethylene / vinyl acetate copolymers and tackifying resins are among others. And a composition in which polyethylene or a low crystalline ethylene / α-olefin copolymer is blended with this, the sealing performance between the container body and the lid is relatively good, and when the lid is peeled off. Widely used because peel strength is generally reasonable.

  For example, Patent Document 1 includes a resin composition having a specific blending ratio of an ethylene / vinyl acetate copolymer, polyethylene, and a tackifier, and a heat sealant of a foamed polystyrene or impact polystyrene container and a lid. The invention of the adhesive composition used in the present invention is disclosed.

  Patent Document 2 discloses a resin composition used for heat-sealing an impact-resistant polystyrene container and a lid body, each comprising an ethylene / unsaturated ester copolymer and a hydrogenated styrene / butadiene copolymer as essential components. The invention is disclosed.

However, recently, there has been a strong demand for optimization of easy opening between the container and the lid, particularly when the peel strength at the time of seal peeling is appropriate, and smooth peeling at an appropriate strength can be achieved even at low temperatures.
In addition, depending on the application, it is desirable that heat sealing be performed at a temperature slightly lower than usual, for example, a temperature around 120 ° C., due to the relationship of materials used for the container body and the coating layer of the lid material, etc. The heat seal characteristics may be different or other characteristics may be required, and a sealing material that can withstand such requirements is desired.

Moreover, since the partial peeling that stops the peeling in the middle can be suitably performed, it is also required to give a smooth and good peeling feeling at the time of peeling. Some seals cannot be sealed well, some have low seal strength, some have sufficient initial seal strength, but the seal strength decreases over time. It was quite difficult to select a sealing material that included problems and completely satisfied the above requirements.
JP 58-15545 A JP 09-188786 A

  As a result of intensive research aimed at developing a sealing material that completely satisfies the above requirements, the present inventors have found that ethylene / vinyl ester copolymer resins such as ethylene / vinyl acetate copolymer resins and ethylene It discovered that the resin composition which consists of a specific compounding quantity ratio of (meth) acrylic acid ester and tackifying resin can satisfy the said requirements, and came to complete this invention based on this knowledge.

Therefore, the object of the present invention is excellent in heat sealability for plastic materials such as expanded polystyrene and impact-resistant polystyrene, and particularly for heat seal materials that are remarkably excellent in sealability even when heat sealing is performed at a lower temperature than conventional products. It is in providing a resin composition.
In addition, the present invention is superior in heat resistance compared to conventional heat seal materials, and has an appropriate peel strength and a smooth and pleasant peel feel against plastic materials such as expanded polystyrene and impact-resistant polystyrene. It aims at providing the resin composition for heat seal materials suitable as a heat seal material between an easily openable lid.

According to the present invention, 30 to 80 parts by mass of an ethylene / vinyl ester copolymer resin (A), 1 to 45 parts by mass of an ethylene / (meth) acrylate copolymer resin (B) and a tackifier resin (C ) 3 to 30 parts by mass (provided that the total amount of the resins (A), (B), and (C) is 100 parts by mass) is provided.
In the present invention, (meth) acrylic acid ester means methacrylic acid ester or acrylic acid ester.

The heat-sealable resin composition of the present invention specifies an ethylene / vinyl ester copolymer resin such as an ethylene / vinyl acetate copolymer resin, an ethylene / (meth) acrylate copolymer resin, and a tackifier resin. The point which is the resin composition obtained by mix | blending with a quantitative ratio makes it the characteristic on a structure.
The above composition is excellent in heat resistance, although it can be heat-sealed at a low temperature compared to similar conventional heat-sealing materials, and is particularly suitable for expanded polystyrene, impact-resistant polystyrene, etc. Excellent peel strength and smooth and pleasant peel feeling.

The resin composition of the present invention preferably has a melt flow rate (MFR) at 190 ° C. under a load of 2160 g (measured according to JIS K7210-1999) of 0.1 to 100 g / 10 min.
The ethylene / vinyl ester copolymer resin (A) is preferably an ethylene / vinyl acetate copolymer resin having a vinyl acetate component unit content of 5 to 30% by mass.
The ethylene / (meth) acrylic acid ester copolymer resin (B) preferably has an ester component unit content of 2 to 48% by mass, and among them, it was obtained by a tubular high pressure polymerization method. Those are particularly preferred.
The adhesive resin (C) is preferably a hydrogenated petroleum resin.
Furthermore, the resin composition of the present invention is particularly preferably used for heat sealing of impact-resistant polystyrene containers.

The resin composition for a heat seal material of the present invention is suitable as a heat seal material used for a plastic container, in particular, a container made of a plastic material such as impact-resistant polystyrene and expanded polystyrene, by the above-mentioned specific configuration, compared to conventional products. It is required as a heat seal material of this kind, such as good heat seal processing at lower temperatures and having a peel strength in an appropriate range with respect to the container body constituting material, and sealing protection of the contents of containers such as food. Maintains almost the same physical properties as conventional products.
However, it has higher heat resistance than conventional products and a smooth and comfortable peeling feeling at the time of peeling.

Hereinafter, preferred embodiments according to the present invention will be described in detail and specifically.
The resin composition for a heat seal material of the present invention comprises an ethylene / vinyl ester copolymer resin (A), an ethylene / (meth) acrylic ester copolymer (B), and a tackifying resin (C) in a specific amount ratio. In combination.

Examples of the ethylene / vinyl ester copolymer resin as component (A) in the resin composition of the present invention include copolymer resins of ethylene and vinyl acetate such as vinyl acetate or ethylene and vinyl propionate. I can do it.
Among these, ethylene / vinyl acetate copolymer resin is preferred in the present invention, and in particular, the content of vinyl ester component units present in the copolymer (in the case of ethylene / vinyl acetate copolymer resin, vinyl acetate component unit content). The ratio is preferably in the range of 5 to 30% by weight, more preferably 9 to 28% by weight.
A vinyl ester content within this range is advantageous because it maintains a good balance between heat seal strength and easy peel properties and has the heat resistance required for filling foods.

  Further, the melt flow rate (measured according to JIS K7210-1999, MFR: 190 ° C., 2160 g load) of this copolymer resin is usually 0.1 to 100, preferably from the viewpoint of extrusion processability and mechanical strength. Is 1 to 50 g / 10 min.

  Next, in the ethylene / (meth) acrylate copolymer resin that is the component (B) of the resin composition of the present invention, (meth) acrylate means acrylic ester and / or methacrylate. To do.

  Specific examples of the (meth) acrylate unit of the copolymer resin (B) include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, N-hexyl acrylate, isohexyl acrylate, n-octyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate And units composed of isobutyl methacrylate, n-hexyl methacrylate, isohexyl methacrylate, n-octyl methacrylate, isooctyl methacrylate, 2-ethylhexyl methacrylate, and the like.

  Further, the melt flow rate (MFR: measured in accordance with JIS K7210-1999, 190 ° C., 2160 g load) of the copolymer resin (B) is 0.1 to 100 g / 10 min. From the viewpoint of the properties and processability of the resulting composition as a heat seal material, 1 to 50 g / 10 min is particularly preferred.

Furthermore, the (meth) acrylic acid ester unit content of the copolymer resin (B) is preferably in the range of 2 to 48% by mass, particularly preferably in the range of 3 to 40% by mass.
When the ester unit content is less than 2% by mass, the heat sealing material has no sufficient sealing performance against the plastic container body constituting material such as high-impact polystyrene and expanded polystyrene, and the feel when peeled off. Even if it is produced by the tubular high pressure polymerization method described below, it is difficult to obtain a copolymer having good heat resistance and heat oil resistance.

In the present invention, the ethylene / (meth) acrylic acid ester copolymer resin (B) may be produced by either autoclave high pressure polymerization method or tubular high pressure polymerization method. It is preferable to use a copolymer resin produced by a high pressure polymerization method.
The copolymer resin obtained by this method has, for example, a copolymer composition and an average molecular weight as compared with an ethylene / (meth) acrylate copolymer produced by another method such as a normal radical polymerization method. Even if they are the same, the melting point is high, but the thermal physical properties such as viscoelastic behavior in the softened to molten state and other attributes are different. Therefore, the composition obtained by blending it is described above. The characteristics of the composition of the present invention can be expressed better.

  The tubular high pressure polymerization method is a method of radical polymerization using a free radical catalyst at a high pressure using a tubular reactor, for example, a method described in JP-A-62-273214 and the like. it can.

The copolymer obtained by the above polymerization method has a relationship between (meth) acrylic acid ester content: E (% by weight) and copolymer melting point: T (° C.) represented by the following formula (I),
−0.8 × E + 115 ≧ T ≧ −0.8 × E + 109 (I)
And has a high melting point and excellent heat resistance as compared with a copolymer having an equivalent composition obtained by another polymerization method.
The copolymer obtained by the above polymerization method has less random arrangement of ethylene units and (meth) acrylic acid ester units than that of a copolymer having good randomness by a normal radical polymerization method, that is, the arrangement is not uniform. The polymer structure and physical properties are somewhat similar to those of block copolymers.
For this reason, it is thought that melting | fusing point and ester unit content have the above relationships.

Examples of the free radical catalyst in the polymerization method include ordinary initiators such as peroxides, hydroperoxides, azo compounds, amine oxide compounds, and oxygen.
Chain transfer agents include hydrogen, propylene, butene-1, C ₁ -C ₂₀ or more saturated aliphatic hydrocarbons and halogen-substituted hydrocarbons such as methane, ethane, propane, butane, isobutane, n-hexane, n- heptane, cycloparaffins, chloroform and carbon _{tetrachloride,} C 1 _{-C 20} or higher saturated aliphatic alcohols, such as methanol, ethanol, propanol and _isopropanol, C 1 _{-C 20} or higher saturated aliphatic Examples include carbonyl compounds such as carbon dioxide, acetone and methyl ethyl ketone and aromatic compounds such as toluene, ethylbenzene and xylene.

  Examples of the tackifying resin that is the component (C) of the resin composition of the present invention include aliphatic hydrocarbon resins, alicyclic hydrocarbon resins, aromatic hydrocarbon resins, polyterpene resins, rosins, and styrene. In addition to petroleum resins, coumarone / indene resins, etc., petroleum resins obtained from the thermal decomposition fraction of petroleum naphtha and hydrogenated products thereof can be mentioned.

  Examples of the aliphatic hydrocarbon resin are obtained by polymerizing a fraction containing at least one mono- or diolefin having 4 to 5 carbon atoms such as 1-butene, isobutene, butadiene, 1,3-pentadiene, and isoprene. Resins that can be used.

  Examples of alicyclic hydrocarbon resins include resins obtained by polymerizing diene components in spent C4 to C5 fractions after cyclization and dimerization, resins obtained by polymerizing cyclic monomers such as cyclopentadiene, aromatics Examples thereof include a resin obtained by hydrogenating a hydrocarbon-based hydrocarbon resin.

Examples of aromatic hydrocarbon resins include resins obtained by polymerizing a fraction containing at least one C8-C10 vinyl aromatic hydrocarbon such as vinyltoluene, indene, α-methylstyrene, or the like. And resins obtained by copolymerizing the above aliphatic hydrocarbon fractions.
Examples of polyterpene resins include α-pinene polymers, β-pinene polymers, dipentene polymers, terpene / phenol copolymers, α-pinene / phenol copolymers, and the like.

Examples of rosins include rosins such as gum rosin, wood rosin and tall oil, and modified products thereof. Examples of modified products include those subjected to modification such as hydrogenation, disproportionation, dimerization, and esterification. it can.
As the styrenic hydrocarbon resin, a low molecular weight resinous polymer obtained by polymerizing one or more styrene monomers such as high-purity styrene, vinyltoluene, α-methylstyrene, and isopropyltoluene. Can be mentioned.

Petroleum resin, by the thermal decomposition of petroleum naphtha, ethylene, propylene, olefins remaining spent C ₅ -C ₉ fraction obtained by fractionating butadiene, generic name for the resulting resinous material by polymerizing remain mixed state However, the main component composition includes aliphatic, aromatic, dicyclopentane, etc., and the composition and properties of the aliphatic hydrocarbon resin, alicyclic hydrocarbon resin already described, Similar to aromatic hydrocarbon resin.
Aromatic and dicyclopentane types are particularly compatible with ethylene / vinyl ester copolymer resins.
Further, those obtained by hydrogenating these petroleum resins are not only improved in the color tone and odor of the resin, but also improved in fluidity, and are particularly suitable as tackifying resins.

  The resin composition of the present invention may contain any resin component such as an ethylene / (meth) acrylic acid copolymer, an ethylene / ethacrylic acid copolymer as long as it does not impair the heat seal characteristics of the present invention. Compound, ethylene maleic acid copolymer, ethylene unsaturated carboxylic acid copolymer resin such as ethylene / fumaric acid copolymer, polyolefin resin such as polyethylene, polypropylene, polybutene, ethylene / α-olefin copolymer, etc. I can do it.

  The blending ratio of the essential resin components (A), (B), and (C) in the resin composition of the present invention is 30 to 80 parts by mass, preferably 35 to 75 parts by mass, of the ethylene / vinyl ester copolymer resin (A). Parts, ethylene / (meth) acrylic acid ester copolymer resin (B) 1 to 45 parts by mass, preferably 5 to 40 parts by mass, and tackifier resin (C) 3 to 30 parts by mass, preferably 5 to 25 parts by mass (however, the total amount of (A), (B), (C) resin is 100 parts by mass).

When the blending amount of the ethylene / vinyl ester copolymer resin (A) exceeds 80 parts by mass, not only the heat resistance of the resulting resin composition is deteriorated, but also the temperature dependency of the heat seal strength is preferably increased. Absent.
On the other hand, when the blending amount of the ethylene / vinyl ester copolymer resin (A) is less than 30 parts by mass, the sealing strength with respect to the container constituent material is not increased, which causes a problem in sealing performance.

Further, when the blending amount of the ethylene / (meth) acrylic acid ester copolymer resin (B) exceeds 45 parts by mass, as in the case of the ethylene / vinyl ester copolymer resin (A), high impact polystyrene, foaming This is not preferable because the heat seal strength for container components such as polystyrene becomes too strong and the unsealing property deteriorates, and the temperature dependence of the heat seal strength becomes too large.
On the other hand, when the blending amount of the component (B) is less than the above lower limit, the blending amount is too small, such as the low-temperature heat-sealability, proper peel strength, and sealing protection of the container contents, which are the characteristics of the composition of the present invention. Various characteristics cannot be realized, and a smooth and comfortable peeling feeling cannot be exhibited at the time of peeling.

When the compounding amount of the tackifying resin (C) exceeds 30 parts by mass, the resulting resin composition is remarkably blocked and becomes difficult to be pelletized.
In addition, not only is the sealing strength as a sealing material too strong, but in the case of food packaging applications, etc., it is not preferable because the amount of oil extraction increases.
On the other hand, when the blending amount is less than 3% by mass, the seal strength tends to be lower than an appropriate value, and in particular, the low-temperature sealability is deteriorated.

  In addition, when mix | blending another resin component as an arbitrary component, about 1-30 mass parts is preferable with respect to 100 mass parts of said (A), (B), (C) total amount.

In the resin composition of the present invention, various additives can be further blended as necessary.
Representative examples of such additives include lubricants and / or roll releasing agents used for the purpose of improving extrudability, roll releasing properties, film slipping properties, and the like.

More specifically, palmitic acid amide, stearic acid amide, behenic acid amide, oleic acid amide, erucic acid amide, oleyl palmidamide, stearyl palmamide, methylenebisstearylamide, methylenebisoleylamide, ethylenebiserucamide, etc. Various amides, polyalkylene glycols such as polyethylene glycol and polypropylene glycol, hydrogenated castor oil, silica, talc, zeolite and other inorganic additives.
These blending amounts are suitably in the range of about 0.1 to 3% by mass in the case of an inorganic additive and about 0.01 to 1% by mass for the other components with respect to the resin component amount.

The resin composition of the present invention is prepared by mixing the essential resin components (A), (B), and (C) described above, and optionally blended resin components and additives simultaneously or sequentially. be able to.
In preparing the resin composition, it is preferable to melt and mix using a single screw extruder, a twin screw extruder, a Banbury mixer, various kneaders, and the mixing order is not particularly limited.

  The resin composition of the present invention thus obtained has a melt flow rate of 0.1 to 100 g / 10 min, particularly 1 to 30 g / min at 190 ° C. under a load of 2160 g in consideration of extrudability, seal strength, boil resistance and the like. It is desirable that it is prepared so as to be about 10 minutes.

  The resin composition of the present invention is suitable as a heat-sealing material for plastic containers, particularly as an easily openable sealing material for containers such as impact-resistant polystyrene and foamed polystyrene and its lid material.

Moreover, when the heat-sealable resin composition of the present invention is used for such applications, it is usually used in a form laminated on various substrates.
Examples of the base material used for this purpose include paper, aluminum, polyester, polyethylene, polypropylene, (high impact) polystyrene, aluminum-deposited polyester, aluminum-deposited polypropylene, and silica-deposited polyester.
Such a substrate need not be a single layer, and may be a laminate of two or more layers.

The laminate thus obtained can be used as various packaging materials.
The heat-sealable resin composition of the present invention is used as a heat-seal material between a single plastic or various easy-open seal-covered containers made of the above-described laminate, particularly between an impact-resistant polystyrene container and a cover material. Sometimes it has excellent sealing properties, easy opening properties, and the like.
Furthermore, it can be effectively used not only for a container made of polystyrene but also for a container of other materials, for example, a container for polypropylene, polyester, polycarbonate, polyvinyl chloride, etc. and a heat seal for a lid.
Such lidded containers can be used for various types of packaging such as instant men, noodles, jelly, pudding, yogurt, honey beans, sour, tofu, lactic acid beverages, Japanese confectionery, processed meats, medicines, medical containers, toners, etc. Can be used.

The present invention will be specifically described by the following examples, but the present invention is not limited to these examples.
The ethylene / vinyl ester copolymer resin (ethylene / vinyl acetate copolymer resin) (A), ethylene / (meth) acrylic acid ester copolymer resin (ethylene / acrylic) used in the following examples and comparative examples. The composition and properties of acid methyl copolymer resin (B), tackifier resin (hydrogenated petroleum resin) (C), other resins, and various additives are as follows.

1) Ethylene / vinyl acetate copolymer resin (EVA): vinyl acetate component content 9.1% by mass, MFR (190 ° C., 2160 g load) 1.7 g / 10 min 2) Ethylene / methyl acrylate copolymer resin ( EMA): Methyl acrylate component content 18% by mass, MFR (190 ° C., 2160 g load) 2.0 g / 10 min 3) Hydrogenated petroleum resin (AM1):
4) Polyethylene (PE): low density polyethylene, MFR 3.8 g / 10 min, density 903 kg / m ³
5) Stearic acid amide (AHT)
6) Erucamide (ELA)
7) Synthetic zeolite

"Example 1"
(A) 63 parts by mass of the above EVA as the component, 10 parts by mass of EMA as the (B) component, 15 parts by mass of AM1 and 10 parts by mass of PE as the (C) component are melt mixed and added to this As the agent, 0.15 parts by mass of AHT (stearic amide), 0.15 parts by mass of ELA (erucic amide) and 1 part by mass of synthetic zeolite powder were added to obtain a resin composition (Composition 1).
This resin composition (Composition 1) was subjected to extrusion lamination at a processing temperature of 240 ° C. and a processing speed of 80 m / min to obtain a polyethylene terephthalate base layer (PET: 12 μm) / polyethylene layer (PE: 20 μm) / composition 1 layer ( 50 μm) was obtained.
This laminate (laminate of composition 1) was heat-sealed on the edge surface of an impact-resistant polystyrene sheet (thickness 2 mm) under the following conditions, and left for 24 hours and then subjected to a peel test (180 °, 15 mm width peel). .
Heat sealing conditions: 0.2 MPa × 0.5 sec × 120-160 ° C.
Table 1 shows the peel strength under each heat seal temperature condition.

"Comparative Example 1"
(A) 73 parts by mass of EVA as component, 15 parts by mass of AM1 and (10) parts by mass of PE as component (C), and melt mixed, 0.15 parts by mass of AHT and 0.15 parts by mass of ELA as additives And 1 part by mass of synthetic zeolite powder were added to obtain a resin composition (Composition 2).
Using this resin composition (Composition 2), the same treatment as in Example 1 was carried out to obtain a laminate having a layer (50 μm) of Composition 2.
This laminate (laminate of composition 2) was heat-sealed on the edge of the same impact-resistant polystyrene container as in Example 1 under the following conditions, and left for 24 hours before being subjected to a peel test (180 °, 15 mm width peel). did.
Heat sealing conditions: 0.2 MPa × 1.0 sec × 120 to 160 ° C.
Table 1 shows the peel strength under each heat seal temperature condition.

表１から明らかなように、エチレン・酢酸ビニル共重合体樹脂（Ａ）と水素添加石油樹脂（Ｃ）にエチレン・アクリル酸メチル共重合体樹脂（Ｂ）を特定量比で組み合わせ配合した実施例１の樹脂組成物は（Ｂ）成分を配合しない比較例１の樹脂組成物に比べ、ヒートシール温度１２０〜１６０℃処理で、その剥離強度が適正な程度に高く、特に比較例品に比して１２０℃程度の低温でヒートシール処理した場合の剥離強度に優れる。

As is apparent from Table 1, an example in which ethylene / methyl acrylate copolymer resin (B) was combined in a specific amount ratio with ethylene / vinyl acetate copolymer resin (A) and hydrogenated petroleum resin (C). Compared with the resin composition of Comparative Example 1 in which the component (B) is not blended, the resin composition of No. 1 has a heat seal temperature of 120 to 160 ° C., and its peel strength is high to an appropriate level. Excellent peel strength when heat-sealed at a low temperature of about 120 ° C.

Claims (7)

  30 to 80 parts by mass of ethylene / vinyl ester copolymer resin (A), 1 to 45 parts by mass of ethylene / (meth) acrylic acid ester copolymer resin (B) and 3 to 30 parts by mass of tackifier resin (C) (However, the total amount of (A), (B), (C) resin is 100 parts by mass).   2. The resin composition according to claim 1, which has a melt flow rate (measured in accordance with JIS K7210-1999) at 190 ° C. under a load of 2160 g of 0.1 to 100 g / 10 minutes.   The resin composition according to claim 1 or 2, wherein the ethylene / vinyl ester copolymer resin (A) is an ethylene / vinyl acetate copolymer resin having a vinyl acetate component unit content of 5 to 30% by mass.   4. The resin composition according to claim 1, wherein the content of the ester component unit in the ethylene / (meth) acrylic acid ester copolymer resin (B) is 2 to 48 mass%.   The resin composition according to claim 4, wherein the ethylene / (meth) acrylic acid ester copolymer resin (B) is obtained by a tubular high-pressure polymerization method.   The resin composition according to any one of claims 1 to 5, wherein the tackifying resin (C) is a hydrogenated petroleum resin.   The resin composition according to any one of claims 1 to 6, which is used for heat sealing a container made of impact-resistant polystyrene.