JPH083526A - Hot-melt composition - Google Patents

Abstract

PURPOSE:To provide a hot-melt composition exhibiting excellent adhesion to a hardly adhesive substrate such as polyvinyl chloride, polypropylene or polyester and having excellent high-temperature adhesion. CONSTITUTION:This hot-melt composition is composed of (1) 10-90wt.% of an ethylene-vinyl acetate copolymer having a [VA] of 5-50, an [MFR] of 0.1-200 and an [mp] satisfying the formula [mp]>110-5Log[MFR]-1.4-[VA] wherein [VA] is vinyl acetate content (wt.%), [MFR] is melt flow rate (g/10min) under 325g load at l25 deg.C and [mp] is the temperature ( deg.C) exhibiting maximum heat- absorption peak by differential scanning calorimeter(DSC), (2) 3-83wt.% of a styrene-based block polymer and (3) 7-87wt.% of a tackifier resin.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a hot melt composition having improved heat resistance and substrate adhesion.

[0002]

2. Description of the Related Art Hot-melt adhesives are solvent-free and have an economic advantage in the process of instant bonding and high-speed bonding, so that they are mainly used in the fields of packaging, bookbinding, woodworking, etc. Used in large quantities. In recent years, it has also partially penetrated into the industrial fields such as automobiles and building materials. Among them, EVA hot-melt adhesives composed of ethylene / vinyl acetate copolymer (EVA), tackifying resin, and wax are packaged by taking advantage of performances such as adhesiveness, cold resistance, coating property, compatibility, etc. Widely used in the fields of bookbinding, plywood, woodworking, etc. However, these EVA-based hot melt adhesives have some performance problems in developing into industrial fields such as automobiles and building materials, specifically, insufficient heat-resistant adhesiveness or polyvinyl chloride / polyester. In reality, there are problems such as insufficient adhesion of base materials to metals and polypropylene.

Various adhesives have been investigated for the difficult-to-adhere substrates such as polyvinyl chloride, polyester and polypropylene. However, for example, in the case of polyvinyl chloride, the solution type adhesives based on chloroprene, NBR, urethane, polyester, etc. are mainly used, and the hot melt adhesives are slightly polyester type. It was nothing more than However, the polyester hot melt adhesives are not satisfactory in flexibility and hydrolysis resistance at low temperatures, and the solution adhesives have problems such as solvent recovery and exhaust, so be careful of working environment. There is a drawback that it is necessary and costly.

Regarding adhesion to polypropylene, ethylene-propylene elastomer or SI
Styrenic block polymers such as S and SBS are used, but they are not always satisfactory in terms of performance in terms of adhesion, cold resistance, coating property, compatibility, etc. Further, these adhesives have a problem that they have insufficient adhesion performance to other substrates such as polyester and polyvinyl chloride. Further, a method of applying an anchor coating agent of polyethyleneimine type, isocyanate type, polybutadiene type or the like to the surface of polypropylene to improve the adhesiveness is also performed, but there are problems such as the use of a solvent.

Regarding the adhesion of polyester, solution type adhesives such as acrylic, polyurethane and isocyanate are used, but there are problems such as solvent use, adhesiveness and cost. As described above, as hot melt adhesives, the performance of adhesives such as polyvinyl chloride, polypropylene, and polyester that are difficult to bond to each other and adhesives used to bond these substrates to metal The reality is that there is nothing satisfactory.

[0006]

Therefore, the present inventors have found that EVA hot melt adhesives have good heat-resistant adhesiveness and good adhesion to poorly adherent substrates such as polyvinyl chloride, polypropylene and polyester. The inventors have made earnest studies to obtain a hot melt composition exhibiting excellent performance.

As a result, a specific ethylene / vinyl acetate copolymer having the same level of VA and melt flow rate and a high melting point as compared with the usual ethylene / vinyl acetate copolymer for hot melt adhesives. It was found that the object can be achieved by combining the block copolymer elastomer and the tackifying resin in a specific compounding combination.

[0008]

MEANS FOR SOLVING THE PROBLEMS The present invention provides (1) the melt flow rate (g / 10 minutes) of an ethylene / vinyl acetate copolymer at 125 ° C. under a load of 325 g [MFR],
Vinyl acetate content (% by weight) [VA], temperature (° C) showing the maximum endothermic peak based on a differential scanning calorimeter (DSC)
Is displayed as [mp], [VA] is 5 to 50,
[MFR] is 0.1 to 200, and [mp] is represented by the formula [mp]> 110-5Log [MFR] -1.4 [V
Ethylene / vinyl acetate copolymers 10-9 satisfying A]
0% by weight and (2) styrenic block polymer 3 to 83
And a (3) tackifying resin of 7 to 87% by weight.

The ethylene / vinyl acetate copolymer having a vinyl acetate content of 50% by weight or less is generally obtained by randomly copolymerizing ethylene and vinyl acetate at high temperature and high pressure in the presence of a radical initiator. The melting point of the copolymer largely depends on the vinyl acetate content (polymerization ratio), but is also influenced by the polymerization conditions. For example, the high-pressure copolymerization is carried out in an autoclave equipped with a stirrer or in a tubular reactor, but in general, the copolymer obtained in the latter has poor randomness and has the same vinyl acetate content. Even the copolymer has a slightly higher melting point than that obtained in the former case. Further, although the degree of influence also varies depending on the vinyl acetate content, when producing a copolymer with a high melt flow rate, it largely depends on the type of chain transfer agent used during polymerization, and also depending on the polymerization temperature, polymerization pressure, etc. A little affected.

The ethylene / vinyl acetate copolymer used in the present invention has a [VA] of 5 to 50, preferably 14 to 45,
[MFR] is 0.1 to 200, preferably 0.5 to 10
0, [mp]> 110-5Log [MFR] -1.4
[VA], preferably [mp]> 112-5Log [M
FR] -1.4 [VA] is satisfied.

[MFR] (JIS K-721)
0) is a value measured at 125 ° C. under a load of 325 g.
Under conditions of 190 ° C. and 2160 g load, which are generally used for measuring the melt flow rate of ethylene / vinyl acetate copolymers, when it exceeds 100 g / 10 min, the measurement error is large and the accurate value is known. It is difficult to say, so it is not a proper condition. Above [MF
The range of R] 0.1 to 200 is approximately equivalent to 10 to 5,500 g / 10 minutes of the melt flow rate (hereinafter referred to as [MFR] ₁₉₀ ) at 190 ° C. and a load of 2160 g, and [MFR] 0.5. The range of up to 100 is 3 of [MFR] ₁₉₀
It corresponds to about 5 to 3,000 g / 10 minutes.

The ethylene / vinyl acetate copolymer used in the present invention has a high melting point, and its melting point is characteristically in the range defined by the above formula in relation to [VA] and [MFR]. Is. That is, a general-purpose ethylene / vinyl acetate copolymer usually has a vinyl acetate content and MFR of
The melting point is higher than the melting point corresponding to the value. By using such a copolymer, excellent performance is exhibited particularly in heat-resistant adhesiveness.

Ethylene having a relatively high melting point in relation to such vinyl acetate content and MFR value
The vinyl acetate copolymer can be produced by selecting the polymerization conditions, and the selection of the chain transfer agent is particularly effective. That is, in the production of ethylene-vinyl acetate copolymer, conventional propylene as a chain transfer agent, instead of olefins such as isobutene, alcohols such as methanol and ethanol, or acetaldehyde,
By using a carbonyl compound such as acetone, it is possible to attain a high melting point of the copolymer produced.

The styrenic block polymer used in the present invention is a block copolymer composed of a styrenic monomer such as styrene or α-methylstyrene and a conjugated diene such as butadiene or isoprene, or a hydrogenated product thereof. It is one kind. Specifically, styrene / butadiene block copolymer, styrene /
Isoprene block copolymer, styrene / ethylene / butene block copolymer (styrene / butadiene block copolymer hydrogenated product), and styrene / ethylene / propylene block copolymer (styrene / isoprene block copolymer hydrogenated product) Examples thereof include a block copolymer having a styrene-based monomer content of 10 to 60 mol% and a conjugated diene content of about 90 to 40 mol%, or a hydrogenated product thereof. Its melt index (ASTM D1238 condition G: 200 ° C., 5
It is preferable to use one having a Kg load of about 1 to 100 g / 10 minutes. For example, Clayton 1101 (SBS),
Clayton 1102 (SBS), Clayton 1107
(SIS), Clayton 1111 (SIS), Clayton 4122 (SBS), Clayton G1651 (SEB
S), Kraton G1652 (SEBS), etc. can be used. The composition ratio, molecular weight, viscosity, etc. of these styrenic block polymers can be widely selected arbitrarily.

The tackifying resin used in the present invention is already known in the field of hot melt adhesives,
Aliphatic hydrocarbon resin, alicyclic hydrocarbon resin, aromatic hydrocarbon resin, polyterpene resin, rosin resin,
Examples thereof include styrene resin and coumarone / indene resin.

The mixing ratio of the ethylene / vinyl acetate copolymer, the styrene block polymer and the tackifying resin is
It can be changed over a relatively wide range, but when comprehensively considering adhesive strength to various substrates, heat resistant adhesiveness, compatibility, etc., (1) ethylene / vinyl acetate copolymer 10
90% by weight, preferably 20 to 70% by weight, (2) styrenic block polymer 3 to 83% by weight, preferably 5
˜70% by weight, (3) tackifying resin 7 to 87% by weight, preferably 15 to 70% by weight.

The viscosity of the hot melt composition of the present invention can be widely set arbitrarily. If a conventional hot melt applicator, a roll coater, or the like is used as a coating device for the substrate to be adhered, a low viscosity of 300,000 cps (180 ° C.) or less is set, and a coating device using an extruder is used. Three
It is desirable to set it to 100,000 cps or higher (180 ° C). The viscosity of the hot melt composition is set by changing the molecular weights of (1) ethylene / vinyl acetate copolymer, (2) styrene block polymer, (3) tackifying resin, and (1), ( It is set by changing the compounding ratios of 2) and (3).

The hot melt composition of the present invention also comprises
A wax may be added for the purpose of improving melt fluidity. Specific examples of such waxes include petroleum waxes such as paraffin wax and microcrystalline wax, natural waxes such as wood wax, carnauba wax, and beeswax, Fischer-Tropsch wax, crystalline polyethylene wax, crystalline polypropylene wax. , Synthetic waxes such as atactic polypropylene. Since the adhesive strength tends to decrease when the amount of wax to be added is excessively increased, the amount of wax is preferably 40% by weight or less, and more preferably 25% by weight or less in the hot melt composition.

If necessary, the hot melt composition of the present invention may contain pigments, dyes, antioxidants, various stabilizers, plasticizers, oils, inorganic fillers and the like.

The hot melt composition of the present invention can be obtained by melt mixing the components simultaneously or in any order. The mixing method is arbitrary, using an extruder, an open roll mill, a Banbury mixer, a kneader, a kneader ruder, a melt mixing tank, etc., a method of mixing under mechanical mixing conditions, a plurality of extruders such as an extruder or a hot melt applicator. It is possible to employ a method of mixing at the time of extrusion using a means.

The hot melt composition of the present invention thus obtained is a halogenated olefin polymer such as polyvinyl chloride or chloroprene rubber, a polyolefin resin such as polyethylene or polypropylene, a polyester resin, a metal, wood or paper. It can be used for adhering various base materials such as cloth and cloth.

For bonding, conventionally used equipment for hot melt adhesive can be used. For example, various coating equipment such as a nozzle type hot melt applicator, a spray type hot melt applicator, a flat nozzle type hot melt applicator, a roll type coater and an extrusion type coater are used.

[0023]

EFFECTS OF THE INVENTION The hot melt composition of the present invention comprises the styrene block polymer and the ethylene / vinyl acetate copolymer having a relatively high melting point in relation to the vinyl acetate content and the MFR value. It has excellent adhesiveness to many adherends such as polyvinyl chloride, polypropylene, and polyester, which are not easy to bond with conventional hot melt adhesives, and has excellent heat resistance. From automobiles, building materials,
It can be expected to be used in various fields as an adhesive for furniture, electric parts, ornaments, bookbinding, packaging materials and the like.

[0024]

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited to these examples. The raw material resins and compounds used in the examples and comparative examples, the method for preparing the composition, the test method and the like are as follows.

1. Raw material resin and compound (1) Ethylene / vinyl acetate copolymer EVA-1; VA content 28% by weight MFR (125 ° C., 325 g load) 8.5 g / 10 minutes (190 ° C., 2160 g MFR 400 g load 400 g)
Melting point: 73 ° C (> 110-5Log [MFR] -1.4)
[VA] = 66.2)

EVA-2; VA content 28% by weight MFR (125 ° C., 325 g load) 8.5 g / 10 min (190 ° C., 2160 g load, MFR 400 g
Melting point 62 ° C. (<110-5 Log [MFR] -1.4
[VA] = 66.2) (Mitsui-Dupont Polychemical Co., Ltd .: Eva Flex 2
10) However, the VA content of EVA resin is measured according to JIS K-
6730, and the measurement of MFR is JIS K-
The measurement was carried out according to 7210. The melting point is determined by a differential scanning calorimeter (DSC method: JIS K-712).
The temperature at which the maximum endothermic peak based on 1) is shown as the melting point.

(2) Styrenic block polymer Styrene / isoprene copolymer (SIS); S / I = 1
4/86, MFR (ASTM D1238 Condition G) 1
0g / 10 minutes (Shell Chemical Co .: Califlex TR1
107)

(3) Tackifying resin Alicyclic hydrocarbon resin; partially hydrogenated system, softening point 100 ° C.
(Arakawa Chemical Co., Ltd .: Alcon M100)

(4) Antioxidant Hindered phenolic antioxidant; manufactured by Ciba-Geigy, Irganox 1010

2. Preparation method of hot melt composition 500g of a mixture prepared by mixing ethylene / vinyl acetate copolymer / styrene block polymer / tackifying resin / antioxidant in a predetermined ratio was charged into a 1 liter beaker, and this was heated at 180 ° C for 1 hour. Melt stir mixing was performed.

3. Test method (1) Method for measuring melt viscosity The melt viscosity of the obtained hot melt composition was measured with a Brookfield viscometer at a temperature of 180 ° C. and a rotation speed of 6 min ⁻¹ .

(2) Method for measuring softening point by ring and ball method The hot melt composition was measured according to JAI 7-991.

(3) Method for measuring low temperature flexibility The hot melt composition was measured according to JAI 7-991.

(4) Method for measuring heat-resistant adhesion (shearing adhesion breaking temperature) 75 g / m ^{2 of a} 0.2 mm thick hot melt composition sheet
Sandwiched between kraft papers and heat sealer at 180 ℃
Sample (25 mm under bonding conditions of × 1 second × 1 kg / cm ² (actual pressure)
A strip of width) was prepared, and the shear adhesive failure temperature was measured according to JIS K-6844 under the conditions of a load of 1 kg and a heating rate of 24 ° C./hour.

(5) Method of measuring adhesion to polyvinyl chloride Adhesion of a 0.2 mm thick hot melt composition sheet between 0.08 mm thick soft polyvinyl chloride (compounded with 35 parts of DOP) sheets and 120 using a heat sealer ℃ × 1 second × 1kg / cm ²
A sample (25 mm wide strip) was prepared under the (actual pressure) bonding condition, and the T-type peel strength was measured with an autograph (tensile tester) in an atmosphere of 23 ° C. (pulling speed 300 mm /
Minutes).

(6) Method for measuring adhesion to polypropylene: A hot-melt composition sheet having a thickness of 0.2 mm is sandwiched between polypropylene sheets having a thickness of 0.2 mm (surface-untreated product), and 180 ° C. for 2 seconds using a heat sealer. Create a sample (25 mm wide strip) under the bonding condition of × 1 kg / cm ² (actual pressure), and
T in an autograph (tensile tester) in a ℃ atmosphere
The mold peel strength was measured (pulling speed 300 mm / min).

(7) Method for measuring adhesion to polyethylene terephthalate: A hot melt composition sheet having a thickness of 0.2 mm is sandwiched between polyethylene terephthalate sheets having a thickness of 0.1 mm (untreated surface), and a heat sealer is used at 180 ° C. × 2 seconds x 1kg / c
A sample (25 mm wide strip) was prepared under the bonding condition of m ² (actual pressure), and the T-type peel strength was measured by an autograph (tensile tester) in an atmosphere of 23 ° C. (pulling speed 300 mm
/ Min).

(8) Method for measuring adhesion to semi-rigid aluminum A hot-melt composition sheet having a thickness of 0.2 mm is sandwiched between semi-rigid aluminum sheets having a thickness of 0.1 mm, and a heat sealer is used at 120 ° C. × 1 second × 1 kg. A sample (25 mm wide strip) was prepared under the bonding condition of / cm ² (actual pressure), and the T-type peel strength was measured by an autograph (tensile tester) in an atmosphere of 23 ° C. (pulling speed 300 mm / Minutes).

[Example 1] EVA-1 was used as the ethylene / vinyl acetate copolymer (EVA), and as shown in Table 1, EVA-1 / SIS / alicyclic hydrocarbon resin / antioxidant = 25 A hot-melt composition was prepared by mixing 500 g of the mixture blended at a ratio of /25/50/0.1 by melt-stirring and mixing according to the above method 2. The obtained hot melt composition was measured for melt viscosity, ring and ball method softening point, low temperature flexibility, shear adhesive failure temperature, and various substrate adhesive properties (T-type peel strength) by the method described above. The results are shown in Table 1.

[Embodiment 2] In the first embodiment, EVA /
A hot melt composition was prepared in the same manner as in Example 1 except that SIS was changed to 40/10, and the physical properties, shear adhesive failure temperature, and adhesive properties of various base materials were evaluated. The results are shown in Table 1.
Shown in

[Comparative Example 1] In Example 1, SIS was not blended and the blending ratio of the hot melt composition was EVA-1.
/ SIS / alicyclic hydrocarbon resin / antioxidant = 50 /
A hot melt composition was prepared in the same manner as in Example 1 except that 0/50 / 0.1 was used, and the physical properties, shear adhesive failure temperature, and adhesive properties of various substrates were evaluated. The results are shown in Table 1.

[Comparative Example 2] In Example 1, EVA-2 was used instead of EVA-1 as the EVA component.
A hot melt composition was prepared in the same manner as in Example 1 except that the composition having the composition shown in 1 was used, and various physical properties and performances were evaluated.
The results are shown in Table 1.

[Comparative Example 3] In Example 2, EVA-2 was used in place of EVA-1 as the EVA component.
A hot melt composition was prepared in the same manner as in Example 1 except that the composition having the composition shown in 1 was used, and various physical properties and performances were evaluated.
The results are shown in Table 1.

[Comparative Example 4] In Comparative Example 1, EVA-2 was used instead of EVA-1 as the EVA component.
A hot melt composition was prepared in the same manner as in Example 1 except that the composition having the composition shown in 1 was used, and various physical properties and performances were evaluated.
The results are shown in Table 1.

[0045]

[Table 1]

Claims (1)

[Claims] (1) Melt flow rate (g / 10 minutes) of an ethylene / vinyl acetate copolymer at 125 ° C. under a load of 325 g is [MFR], vinyl acetate content (% by weight) is [VA], and differential When displaying the temperature (° C.) showing the maximum endothermic peak based on a scanning calorimeter (DSC) in [mp], [VA] is 5 to 50 and [MFR] is 0.1 to 20.
0 and [mp] is of the formula [mp]> 110-5Log [MFR] -1.4 [V
A hot-melt composition comprising 10 to 90% by weight of an ethylene / vinyl acetate copolymer satisfying A], (2) 3 to 83% by weight of a styrene block polymer, and (3) 7 to 87% by weight of a tackifying resin.