JPH0649291A - Hot melt composition - Google Patents

Abstract

PURPOSE:To provide the hot melt composition containing ethylene-vinyl acetate copolymer as a main component, low in its melt viscosity even when the amount of a high melting point wax is reduced or eliminated, and excellent in hot adhesion resistance. CONSTITUTION:The hot melt composition comprises two kinds of ethylene-vinyl acetate copolymers (A) and (B), the copolymer (A) having a [VA] of 23-45 and a [MFR] of 0.1-200, and the component (B) having a [VA] of 5-22, a [MFR] of 10-400, and a [mp] higher than a temperature defined by a relation equation of [MFR] and [VA] (wherein [MFR] exhibits a melt flow rate (g/10min) at 125 deg.C under a load of 325g; [VA] exhibits the content of the vinyl acetate component; [mp] is a temperature ( deg.C) exhibiting the maximum heat absorption peak based on a differential scanning calorimeter). The hot melt composition may further be compounded with a tackifying resin and/or a wax.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to hot melt compositions having improved heat resistant adhesion.

[0002]

2. Description of the Related Art Ethylene / vinyl acetate copolymer (hereinafter referred to as E
A hot melt adhesive composed of a tackifying resin and a wax is widely used in fields such as packaging, bookbinding, plywood, and woodworking. In this basic formulation, the wax formulation is effective in lowering the melt viscosity and imparting heat-resistant adhesion, but there is a limit to the improvement in heat-resistant adhesion by blending the wax, and the adhesive itself becomes brittle and cold-resistant. Decreasing the adhesiveness is a problem.

Although a method of remedying this drawback by using a high-purity, high-melting-point wax has been adopted in some cases,
It is not desirable to mix a large amount because it is expensive,
The advent of a prescription for reducing the amount used or an alternative prescription has been desired.

[0004]

Therefore, the present inventors have made it possible to reduce the amount of the high melting point wax used, or to achieve a low melt viscosity without using the high melting point wax and to obtain a hot adhesive excellent in heat resistance. Diligent studies were conducted to obtain a melt composition.

As a result, a blend of a normal hot melt grade ethylene / vinyl acetate copolymer with a specific ethylene / vinyl acetate copolymer having a slightly low vinyl acetate content, a high melting point and a low melt viscosity is prepared. I learned that the purpose can be achieved by using it.

[0006]

The present invention comprises two or more ethylene / vinyl acetate copolymers, and is used at 125 ° C., 32 ° C.
Melt flow rate (g / 10 minutes) at a load of 5 g is [MFR], vinyl acetate content (% by weight) is [VA],
When the temperature (° C.) at which the maximum endothermic peak based on the differential scanning calorimeter (DSC) is displayed in [mp], ethylene having [VA] of 23 to 45 and [MFR] of 0.1 to 200
Vinyl acetate copolymer (A) 5 to 95% by weight, and [VA]
Is 5-22, [MFR] is 10-400, and [mp] satisfies the formula [mp]> 112-5 log [MFR] -1.4 [VA]. B) 95-
It relates to a hot melt composition consisting of 5% by weight.

According to the present invention, 100 parts by weight of such an ethylene / vinyl acetate copolymer component is added to the tackifying resin 0.
˜150 parts by weight and / or 0 to 100 parts by weight of wax are blended.

The ethylene / vinyl acetate copolymer having a vinyl acetate content of 45% 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 above high-pressure copolymerization is carried out in an autoclave equipped with a stirrer or in a tubular reactor. In general, the copolymer obtained by the latter has poorer randomness and the same vinyl acetate content. Even the polymer has a slightly higher melting point than the former one. The degree of influence also varies depending on the vinyl acetate content, but 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 slightly depending on the polymerization temperature, polymerization pressure, etc. Affected by.

The ethylene / vinyl acetate copolymer (A) used in the present invention includes typical commercial hot-melt grades and has a [VA] of 23 to 45, preferably 25 to 45, although it varies depending on the purpose of use. 35, [MFR] is 0.
It is in the range of 1 to 200, preferably 0.5 to 100.

[MFR] (JIS K-721)
0) is a value measured at 125 ° C. and a load of 325 g.
Under the conditions of 190 ° C and 2160g load, which are generally used for measuring the melt flow rate of ethylene / vinyl acetate copolymers, there is a large measurement error at 1000g / 10 min. It is difficult to say, so it is not an appropriate condition. Above, MFR
The range of 0.1 to 200 generally corresponds to 10 to 5500 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.
The range of 0.5 to 100 is 35 to 300 of [MFR] ₁₉₀ .
It corresponds to about 0 g / 10 minutes. The copolymer having the above properties can also be obtained from the market.

The ethylene / vinyl acetate copolymer (B) in the present invention has a [VA] of 5 to 22, preferably 10.
19, [MFR] is 10 to 400, preferably 15 to 2
00, [mp]> 112-5 log [MFR] -1.4
[VA], preferably 115-5 log [MFR]-
1.4 [VA] <[mp] <125-5 log [MFR]
It satisfies −1.4 [VA]. Here, 10-400 of [MFR] is 450- of [MFR] ₁₉₀
Corresponding to about 10000g / 10 minutes, 15-200,
This corresponds to about 650 to 5500 g / 10 minutes of [MFR] ₁₉₀ .

In the copolymer (B), [VA] is small, [MFR] is large, and the melting point is in the range represented by the above formula defined by the relationship between [VA] and [MFR]. Characteristically, the use of such a copolymer shows excellent performances in low melt viscosity and heat-resistant adhesiveness.

The chain transfer agent used in the production of ethylene / vinyl acetate copolymer includes olefins such as propylene and isobutene, alcohols such as methanol and ethanol, carbonyl compounds such as acetaldehyde and acetone, By selecting these appropriately, the copolymer defined in (A) or (B) can be easily produced. Generally, in the production of a copolymer having a large MFR, the [mp] of the produced copolymer is greatly affected by the type of chain transfer agent.

The use ratio of the copolymer (A) and the copolymer (B) depends on the desired properties, but it is (A) /
(B) (weight ratio) is 5 to 95/95 to 5, preferably 2
The range is 5 to 90/75 to 10.

The hot melt composition of the present invention may contain a tackifying resin and / or wax for the purpose of adjusting melt viscosity, tackiness, adhesiveness and the like. In particular, it is preferable to use the tackifying resin in combination, and it is preferable to add it in a proportion of 0 to 150 parts by weight, preferably 50 to 120 parts by weight, based on 100 parts by weight of the total amount of both components of the copolymer (A) and (B). . The composition of the present invention does not require the use of wax, but the copolymer (A) (B) is used for adjusting the melt viscosity.
You may mix | blend in a ratio of 0-100 weight part, especially 0-70 weight part with respect to 100 weight part of total amounts of both components.

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

[0017]

According to the present invention, it is possible to obtain a hot melt composition having a low melt viscosity and excellent heat resistant adhesiveness. Particularly, in the conventional hot melt adhesive formulation, the amount of wax can be reduced or omitted, and the desired properties can be obtained without using expensive high melting point wax. Taking advantage of such characteristics, the hot melt composition of the present invention can be used as a hot melt adhesive, a hot melt coating agent and the like in various fields such as packaging, bookbinding, plywood and woodworking.

[0018]

EXAMPLES The present invention will be described below with reference to examples, but 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 (A) EVA-1: VA content 28% by weight MFR (125 ° C., 325 g load) 8.5 g / 10 min (190 ° C., 2180 g MFR at load) About 40
Equivalent to 0 g / 10 minutes) Melting point 62 ° C (Evaflex 210, manufactured by Mitsui DuPont Polychemical Co., Ltd.)

EVA-2: VA content 28% by weight MFR (125 ° C., 325 g load) 20 g / 10 minutes (1
Approximately 800g of MFR at 90 ℃ and 2160g
/ Equivalent to 10 minutes) Melting point 70 ° C (DuPont: Erbax 205W)

(2) Ethylene / vinyl acetate copolymer (B) EVA-2: VA content 14% by weight, MFR (125 ° C., 325 g load) 80 g / 10 minutes (1
MFR at 90 ° C and 2160g load is approximately 2500g
/ 10 minutes) Melting point 89 ° C. (DuPont: Erbax 500 W)

However, the VA content of the EVA resin was measured according to the saponification method, and the MFR was measured according to JIS K-7210. Further, the melting point was measured with the melting point being the temperature at which the maximum absorption peak based on the analysis method using a differential scanning calorimeter (DSC method: according to JIS K-7121).

(3) Tackifying resin Rosin ester: Rosin-pentaerythritol ester, softening point 115 ° C. (Hitachi Kasei Polymer Ltd .: Tespol 1072)

(4) Wax Wax-1: General-purpose paraffin wax, melting point 69 ° C.
(155 ° F) (Nippon Seiwa Co., Ltd .: Paraffin wax 1
55)

Wax-2: High-purity refined paraffin wax, melting point 75 ° C. (Nippon Seiwa Co., Ltd .: HNP-9)

(5) Antioxidant Hindered phenolic antioxidant: manufactured by Ciba-Gaigi Co.,
Irganox 1010

2. Method for Preparing Hot Melt Composition 1000 g of a mixture prepared by mixing EVA resin / tackifying resin / wax / antioxidant in a predetermined ratio was charged into a 2 liter beaker, and the mixture was melted and stirred at 180 ° C. for 1 hour.

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 preparing adhesive test piece Hot melt composition was hot melt oven time
Using a tester (Asahi Chemical Synthetic Co., Ltd.), coating temperature 180
℃, coating amount 0.030g / 10mm, coating speed 7.5m
/ Min, oven time 3.5 seconds, set time 3.
A bead-like coating was applied under the condition of 0 seconds, and a bonding adhesive test piece was prepared for the corrugated cardboard cover material (general liner: 220 g / m ² ) (adhesive test piece size: 100 mm × 10).
0 mm). This adhesive test piece was cut into a size of 25 mm × 100 mm to obtain a tensile test sample for evaluating adhesive strength.

(4) Method of evaluating adhesive strength of adhesive test piece Tensile speed of 300 mm / m using a tensile tester with a constant temperature bath
In, the adhesive test piece (corrugated board cover material / hot-melt adhesive / corrugated board cover material) was pulled by the T-type peeling method under the condition of the measurement atmosphere temperature of 50 ° C., and the material of the corrugated board cover material after peeling was then destroyed. The heat resistance was evaluated by measuring the rate.

Example 1 As shown in Table 1, EVA-1 / EVA-2 / rosin ester / wax-1 / antioxidant = 35/10/40 /
1000 g of a mixture blended at a ratio of 15 / 0.1 was added to 2. A hot melt composition was prepared by melt-stirring and mixing by the method described in 1.

The hot melt composition thus obtained was mixed with the above 3.
The melt viscosity, the softening point by the ring and ball method, and the evaluation of the adhesive strength were carried out by the method described above. The results are shown in Table 1.

Example 2 A hot melt composition was prepared in the same manner as in Example 1 except that the mixing ratio of EVA-1 / EVA-3 in Example 1 was changed and the composition shown in Table 1 was changed. It was measured. The results are shown in Table 1.

Example 3 EVA-2 as ethylene-vinyl acetate copolymer (A)
Was used to prepare a hot melt composition having the composition shown in Table 1 in the same manner as in Example 1, and the physical properties were measured. The results are shown in Table 1.

Example 4 A hot melt composition was prepared in the same manner as in Example 1 except that the amount of wax-1 was increased and the composition shown in Table 1 was used.
The physical properties were measured. The results are shown in Table 1.

Example 5 A hot melt composition was prepared in the same manner as in Example 1 except that a highly pure purified paraffin wax, wax-2, was blended as a wax in the proportions shown in Table 1, and the physical properties were measured. The results are shown in Table 1.

Comparative Example 1 No ethylene / vinyl acetate copolymer (B) was blended.
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 the physical properties were measured. The results are shown in Table 1.

Comparative Example 2 A hot melt composition was prepared in the same manner as in Example 1 except that the ethylene / vinyl acetate copolymer (B) was not blended and a highly purified purified paraffin wax was blended as a wax. The product was prepared and the physical properties were measured. The results are shown in Table 1.

[0040]

[Table 1]

Claims (2)

[Claims] 1. A melt flow rate (g / 10 min) at 125 ° C. under a load of 325 g, [MFR], and a vinyl acetate content (% by weight) [VA, which is composed of two or more ethylene / vinyl acetate copolymers. ], When the temperature (° C.) at which the maximum endothermic peak based on the differential scanning calorimeter is displayed in [mp], ethylene / vinyl acetate having [VA] of 23 to 45 and [MFR] of 0.1 to 200 Polymer (A) 5 to 95% by weight
And ethylene-acetic acid whose [VA] is 5 to 22, [MFR] is 10 to 400, and [mp] satisfies the formula [mp]> 112-5 log [MFR] -1.4 [VA] Vinyl copolymer (B) 95-
A hot melt composition comprising 5% by weight. 2. An ethylene / vinyl acetate copolymer component 10
The hot melt composition according to claim 1, further comprising 0 to 150 parts by weight of a tackifying resin and / or 0 to 100 parts by weight of a wax per 0 parts by weight.