JPH0623359B2 - Hot melt adhesive composition - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a novel hot melt adhesive composition.

2. Description of the Related Art A conventional hot melt adhesive is solid at room temperature, and is heated and melted at the time of use to be applied to various substrates, adhered, and cooled to solidify to develop an adhesive force. The hot melt adhesive is usually an ethylene-vinyl acetate copolymer (EVA) as a base polymer, an ethylene-based copolymer such as an ethylene-acrylate copolymer, polyethylene, a thermoplastic rubber, polyamide, polyurethane, polyester or the like. A thermoplastic polymer material is used, and a tackifying resin and various waxes as a viscosity modifier are mixed therein.

As the base polymer, an ethylene-based copolymer such as EVA and ethylene-acrylate is generally used from the viewpoints of flexibility, heat stability, cost, and the like. As the tackifying resin, rosin-based, terpene-based natural resins or various petroleum resins are used. In particular, rosin-based resins such as rosin esters have been conventionally favored because of their excellent adhesive strength at room temperature (hereinafter, referred to as room-temperature adhesive strength), but they are stable in heating and adhere at a high temperature of about 50 to 70 ° C. The strength (hereinafter, referred to as high temperature adhesive strength) is not satisfactory. On the other hand, when using a terpene-based resin mainly terpene phenol resin, the heating stability,
Although it is quite excellent in high temperature adhesive strength, it is not satisfactory in room temperature adhesive strength and odor. Furthermore, various petroleum resins obtained by polymerizing cheap petroleum fraction as a raw material are used as a tackifying resin in place of rosin-based and terpene-based resins, but they are stable in heating and adhesive at room temperature. It is not yet comparable to the above natural resin in various characteristics such as.

As described above, any of the conventionally known tackifying resins is inferior in at least one of heat stability, high temperature adhesive strength and room temperature adhesive strength, and a satisfactory hot melt adhesive is still obtained. Not in the present situation.

Means for Solving the Problems In order to develop a new useful hot-melt adhesive that has improved the above-mentioned various drawbacks, the present inventors have developed a rosin-based resin that is relatively excellent in various properties among conventionally known tackifying resins. We focused ourselves and conducted a thorough study. As a result, when a specific rosin-based resin is used as the tackifying resin, a hot melt adhesive excellent in heat stability, high temperature adhesive strength, and room temperature adhesive strength is obtained, and all of the above-mentioned various drawbacks are solved at the same time. It was found that the present invention has been completed.

That is, the present invention provides a hot-melt adhesive composition containing an ethylene copolymer, a wax and a tackifying resin as main components, wherein the tackifying resin has a softening point of 155 to 20.
0 ° C. and (A) a reaction product of a rosin phenol resin and a metal compound, (B) a reaction product of a rosin phenol resin and a polyhydric alcohol, and (C) a rosin phenol resin and a polyhydric alcohol, and The present invention relates to a hot melt adhesive composition, which is at least two kinds or (C) selected from reaction products with a metal compound.

In the composition of the present invention, the tackifying resin has a softening point of 1
55 to 200 ° C. and (A) a reaction product of a rosin phenol resin and a metal compound (hereinafter referred to as resin (A)), (B) a reaction product of a rosin phenol resin and a polyhydric alcohol (hereinafter , Resin (B)), and (C) at least two kinds selected from reaction products of rosin phenol resin with polyhydric alcohol and metal compound (hereinafter referred to as resin (C)) or resin (C) is used. That is, the intended purpose of the present invention is achieved.

In the present invention, the rosin phenol resin includes both so-called rosin phenol resin obtained by reacting rosin and phenols, and so-called rosin-modified phenol resin obtained by reacting resol type phenol resin and rosin. And both can be used effectively.

Of these, the former so-called rosin phenol resin is
It is a product obtained by reacting rosin with phenols in the presence of an acid catalyst such as sulfuric acid, boron trifluoride, hydrogen chloride, p-toluenesulfonic acid, methanesulfonic acid, etc., and adding phenols to rosin. It may be heated to be dimerized or trimerized. here,
The molar ratio of rosin and phenols charged is preferably rosin: phenols = 1: 0.8 to 1: 1.5. The addition reaction is usually performed at 130 to 200 ° C. for 4 to 10 ° C.
It takes about 250 to 30 hours, and the multimerization reaction is usually 250 to 30.
It is good to carry out at about 0 ° C. for about 2 to 8 hours. The latter so-called rosin-modified phenol resin is a reaction between a resol-type phenol resin and rosin in the presence or absence of an acid catalyst such as sulfuric acid, boron trifluoride, hydrogen chloride, paratoluenesulfonic acid, or methanesulfonic acid. It is a resin that can be obtained at most. Here, the charging ratio at the time of the reaction of the resol type phenol resin and the rosin is preferably about 10 to 50 parts by weight of the resol type phenol resin to 100 parts by weight of the rosin, and the reaction is usually performed at about 200 to 270 ° C. It is better to carry out for about 1 to 8 hours.

Examples of the rosin include various known rosins such as gum rosin, wood rosin, tall oil rosin, and polymerized rosin. Further, as the phenols, any phenol, cresol, β-naphthol, para-t-butylphenol, paraoctylphenol, paranonylphenol and the like which can be added to rosin can be used.

The resin (A) is a resin in which a rosin phenol resin and a metal compound react to produce a metal salt of the resin, and 50 to 100 of the carboxyl groups of the rosin phenol resin are contained.
It is preferable that about equivalent% of the metal salt is used. Therefore, the resin
(A) may contain an unreacted carboxyl group. When the metal chlorination rate of all the carboxyl groups of the resin (A) is much smaller than 50 equivalent%, the improvement in high temperature adhesive strength of the obtained hot melt adhesive is small. The type of the metal compound is not particularly limited, and any compound capable of forming a metal salt with a carboxyl group can be effectively used, and examples thereof include monovalent metals such as lithium and divalent metals such as zinc and calcium. Various compounds such as trivalent metals such as aluminum and aluminum can be used. Among them, it is preferable to use a divalent metal compound, especially a zinc compound.
That is, when a divalent metal compound, especially a zinc compound, is used, the heating stability is superior to other monovalent or trivalent metal compounds. The form of the metal compound is not particularly limited, but the metal oxide, chloride, hydroxide,
It is preferably used in the form of sulfate or the like.

The resin (A) is produced, for example, by the following method. That is, the rosin phenol resin is dissolved in a soluble solvent such as toluene, xylene, and ethyl acetate, and then a predetermined amount of the metal compound is added to this solution so that the metal chloride ratio of the carboxyl group of the rosin phenol resin falls within the above range. A resin (A) is obtained by adding the deionized water and performing a neutralization reaction, and after the completion of the reaction, removing the unreacted metal compound in excess by removing the solvent and water. The neutralization reaction is carried out under reflux of deionized water, i.e. 95-10.
It is good to carry out at about 0 degreeC for about 4 to 5 hours.

The resin (B) is obtained by reacting a rosin phenol resin with a polyhydric alcohol to form a polyhydric alcohol ester of the resin, and esterifies about 20 to 100 equivalent% of the carboxyl groups of the rosin phenol resin. What is obtained by this is good. Therefore, the resin (B) may contain an unreacted carboxyl group. When the esterification rate of the carboxyl group of the resin (B) is much smaller than 20 equivalent%, the room temperature adhesive strength of the obtained hot melt adhesive is lowered. In the present invention, a polyhydric alcohol is used for the esterification reaction. When a monohydric alcohol is used, the softening point of the obtained resin (B) becomes low, which is not preferable. The polyhydric alcohol used is not particularly limited, and examples thereof include dihydric alcohols such as ethylene glycol and diethylene glycol,
Any of trihydric alcohols such as glycerin, trimethylolethane and trimethylolpropane, tetrahydric alcohols such as pentaerythritol and the like can be used, and of these, it is preferable to use glycerin and the like. The resin (B) is produced, for example, by the following method. That is, in an inert gas, in the presence or absence of an acidic esterification catalyst such as p-toluenesulfonic acid or phosphoric acid or an alkaline esterification catalyst such as lithium hydroxide or magnesium hydroxide, the carboxyl group of the rosin phenol resin is not present. The resin (B) is obtained by charging a predetermined polyhydric alcohol having an esterification rate of the group within the above range into a reaction vessel, heating it, and removing water generated by the reaction to the outside of the reaction system. The heating reaction is usually 150 to 3
It is preferable to carry out at about 00 ° C. for about 2 to 15 hours.

The resin (C) is produced by reacting a rosin phenol resin with a polyhydric alcohol and a metal compound, and is 5 to 80 equivalent% of the carboxyl group of the rosin phenol resin.
It is preferable that the degree is esterified and about 10 to 70 equivalent% is metal chloride. Therefore, the resin (C) may contain an unreacted carboxyl group. When the esterification rate of the carboxyl group of the resin (C) is much smaller than 5 equivalent%, the room-temperature adhesive strength of the obtained hot-melt adhesive is lowered, and when it is larger than 80 equivalent%, the high temperature adhesive strength is high. descend. Also, resin (C)
If the metal salification rate of the carboxyl group is less than 10 equivalent%, the temperature adhesive strength is decreased, and if it is more than 70 equivalent%, the room temperature adhesive strength is decreased. Examples of the metal compound and the polyhydric alcohol used include the same ones as those used in the production of the resin (A) or the resin (B). The resin (C) may be produced by passing the resin (A) production method and the resin (B) production method in any order.

The softening points of the resins (A), (B) and (C) thus obtained are 155 to 200 from the viewpoints of room temperature adhesive strength and high temperature adhesive strength, respectively.
℃

In the present invention, as the tackifying resin (A), (B),
By using at least two kinds of (C) or the resin (C), various performances of the hot melt adhesive are sufficiently improved. In particular, the tackifying resin used in the composition of the present invention is excellent in room-temperature adhesive strength, odor, etc., as compared with the conventional terpene phenol resin. Conventionally, no tackifying resin having such various properties has been developed.

The ratio of the resins (A), (B) and (C) used as tackifying resins is
Although it cannot be determined unconditionally, 20 equivalent% or more, preferably 50 equivalent% or more of the total number of carboxyl groups in the tackifying resin reacts with the polyhydric alcohol or metal compound, and the polyhydric alcohol ester and the metal salt. Equivalent ratio to 1
It is preferable that the time is 0:90 to 90:10. When the ratio of polyhydric alcohol ester is much smaller than 10,
The room-temperature adhesive strength of the obtained hot-melt adhesive composition decreases, and when it is much larger than 90, the high-temperature adhesive strength tends to decrease.

In the present invention, a conventionally known tackifying resin may be used in combination with the essential tackifying resin, if necessary. In particular, if rosin esters are used together as the tackifying resin, heating stability and room temperature adhesive strength can be further improved.

Here, the rosin ester means a product obtained by a known method such as rosin and a polyhydric alcohol, for example, the same method as the esterification used in the production of the resin (B). Examples of rosins that can be used here include natural rosins such as gum rosin, wood rosin and tall oil rosin, and 1.3 to 20 mol% relative to these natural rosins.
The partially fumarized rosin and the partially maleated rosin obtained by heating and reacting fumaric acid or maleic anhydride of, and modified rosins such as hydrogenated rosin and disproportionated rosin are mentioned. When the rosin ester is used in combination with the essential tackifying resin, both improve the heating stability and room temperature stability of the hot melt adhesive composition of the present invention, but among them, the disproportionated rosin ester was used. The case is particularly good.

When the rosin ester is used in combination as the tackifying resin, it is preferable to use it in an amount of up to 50% by weight of the total amount of the tackifying resin and the rosin ester, which are essential in the present invention. If the rosin ester is used in excess of this ratio, the high temperature adhesive strength tends to decrease. A preferable usage rate of the rosin ester is about 30 to 50% by weight.

The hot melt adhesive composition of the present invention is a resin (A), a resin
At least two types or resins selected from (B) and resin (C)
It is prepared by using (C) as an essential tackifying resin, the ethylene-based copolymer and waxes as main components, and heating and mixing these components. As the ethylene-based copolymer used here, any of those conventionally used as a base polymer can be used. For example, a copolymer of ethylene and one or more of monocarboxylic acid vinyl ester and acrylic acid ester can be used. Coalescence can be preferably used. The content of polar components such as monocarboxylic acid ester and acrylic acid ester in the ethylene copolymer is about 10 to 60% by weight, preferably 15 to 4%.
5% by weight, and the melt index (MI) of the copolymer is about 0.1 to 1000, preferably 1 to 5
00. The melt index here is AST.
According to MD-1238, 1 at 190 ° C, load 2160g
The number of grams flowed out in 0 minutes. As the waxes used in the composition of the present invention, any of the conventional waxes can be used. For example, petroleum wax such as paraffin wax and microcrystalline wax, natural wax, polyethylene wax, polypropylene wax, atactic wax. Examples thereof include synthetic waxes such as polypropylene wax. These can be appropriately selected according to the use of the obtained hot melt adhesive.

The blending ratio of the ethylene copolymer, waxes and tackifying resin (including an essential resin and a resin optionally used in combination) in the hot melt adhesive composition of the present invention is not particularly limited, and the obtained hot Although it can be selected from a wide range according to the purpose of use, application, etc. of the melt adhesive, a hot melt adhesive composition excellent in both room temperature adhesive strength and high temperature adhesive strength, which is a feature of the present invention, is prepared by the following formulation. can get.

For example, when it is used as an adhesive for paper, various plastic films, aluminum foil, and other packaging-related materials, it can be used with a relatively small amount of ethylene copolymer. Usually, for these applications, it is preferable to mix the waxes in an amount of 10 to 200 parts by weight and the tackifying resin in an amount of 20 to 400 parts by weight with respect to 100 parts by weight of the ethylene copolymer. In addition, when relatively strong adhesive strength is required for woodworking and bookbinding, a hot melt with high adhesiveness that is rich in rigidity and flexibility by blending mainly ethylene copolymer and tackifying resin An adhesive can be prepared. In this case, the compounding ratio is 20 to 200 parts by weight, preferably 50 to 180 parts by weight and waxes 10 to 100 parts by weight, preferably 20 to 50 parts by weight, based on 100 parts by weight of the ethylene copolymer. Good to do.

Furthermore, an antioxidant, an ultraviolet absorber, etc. may be appropriately added to the hot melt adhesive composition of the present invention, if necessary.

The coating method of the adhesive composition of the present invention is the same as that of a normal hot melt adhesive, and various coating methods such as roll coating, gravure coating, and dip coating can be adopted.

EFFECTS OF THE INVENTION According to the present invention, the following remarkable effects can be obtained particularly by blending the specific tackifying resin as described above.

That is, the composition of the present invention is excellent in heating stability which is a basic performance required in a hot melt adhesive composition, has little coloring and does not skin, and has good compatibility with a base polymer and a wax. It has all the conditions of no phase separation, no odor during coating, does not adversely affect the working environment, and has excellent room-temperature adhesive strength, as well as excellent high-temperature adhesive strength. It has excellent performances such as the provision of hot melt adhesives.

In particular, the present invention provides a hot melt adhesive composition that can withstand use in a wide temperature range from normal temperature to high temperature, and development of a hot melt adhesive excellent in such properties has been earnestly desired. It is in good agreement with the current situation and is very effective. The reason why the composition of the present invention is excellent in both room temperature adhesive strength and high temperature adhesive strength is not clear, but the metal salt of the rosin phenol resin having a high softening point imparts adhesive strength at high temperature, and It is considered that the decrease in adhesive strength at room temperature, which occurs on the other hand, is supplemented by using a polyhydric alcohol ester of rosin phenol resin, and the adhesive strength at room temperature and high temperature are simultaneously satisfied.

EXAMPLES The present invention will be described in more detail below with reference to Production Examples, Examples and Comparative Examples, but the present invention is not limited to these examples. In the examples, all parts and% are by weight unless otherwise specified.

Production Example 1 A reaction vessel equipped with a stirrer, a cooling pipe, a dropping funnel and a nitrogen introducing pipe was charged with 100 parts of rosin phenol resin (manufactured by Arakawa Chemical Industry Co., Ltd., trade name "Tamanor 803L") and 100 parts of toluene. After stirring and dissolving, the temperature in the system was raised to 90 ° C. while stirring. Next, 4 parts of zinc oxide and 8 parts of deionized water were added, the temperature in the system was raised to 100 ° C., and the reaction was carried out under reflux of deionized water for 5 hours. After the reaction was completed, unreacted zinc oxide was removed by passing, and then the solvent and water were distilled off under reduced pressure to obtain a zinc salt of a rosin phenol resin. The softening point of the resin is 183.0 ° C.,
The zinc chloride ratio was 96 equivalent% (resin (A)).

Production Example 2 100 parts of rosin phenol resin (“Tamanor 803L”) and 3 parts of glycerin were charged in the same reaction vessel as in Production Example 1, and then heated in a nitrogen stream until the temperature in the system reached 240 ° C. After reacting for 3 hours at the same temperature, 275 more
The temperature was raised to 0 ° C. and the reaction was carried out at the same temperature for 5 hours. Then, the low boiling fraction was removed under reduced pressure to obtain a glycerin ester of rosin phenol resin. The softening point of the resin is 176.5 ° C.
And the esterification rate was 63 equivalent% (resin (B)).

Production Example 3 100 parts of rosin phenol resin (“Tamanor 803L”) and glycerin 1.5 were placed in the same reaction vessel as in Production Example 1.
After charging the parts, the system was heated under a nitrogen stream until the temperature in the system reached 240 ° C. After reacting at the same temperature for 3 hours, 2 more
The temperature was raised to 75 ° C., and the reaction was carried out at the same temperature for 5 hours. afterwards,
The low-boiling fraction was removed under reduced pressure to obtain glycerin ester of rosin phenol resin. Further, 100 parts of the glycerin ester of the obtained rosin phenol resin and 100 parts of toluene were charged in the same reaction vessel, and then heated while the system temperature reached 90 ° C. while melting. Then
Add 2.5 parts of zinc oxide and 5 parts of deionized water, and add 1 part to the system.
The temperature was raised to 00 ° C., and the reaction was performed for 5 hours under reflux of deionized water. After completion of the reaction, unreacted zinc oxide was removed by passing, and then the solvent and water were distilled off under reduced pressure to obtain a reaction product of rosin phenol resin with glycerin and zinc oxide. The obtained resin had a softening point of 160.0 ° C., an esterification rate of 35 equivalent% and a zinc chloride rate of 58 equivalent% (resin (C)).

Example 1 "EVA # 150" (polar component content 33%, MI2
5, Mitsui Polychemical Co., Ltd.) 40 parts, 20 parts of the zinc salt of the rosin phenol resin obtained in Preparation Example 1, Preparation Example 2
20 parts of the glycerin ester of the rosin phenol resin and "Polywax 2000" (polyethylene wax, manufactured by Toyo Ink Mfg. Co., Ltd.) obtained in Step 2 were placed in a beaker and used as an antioxidant for EVA "Irganox 10".
10 "(manufactured by Ciba Geigy) was added to 180
The composition of the present invention (compound) was obtained by thoroughly mixing at ° C. Then, the above composition was applied to an aluminum foil with a bar coater so as to have a thickness of 30 μm to prepare a test piece.

Examples 2 to 9 Various hot melt adhesive compositions (compounds) were prepared in the same manner as in Example 1 except that the composition of the tackifying resin was changed as shown in Table 1 in Example 1. Similarly, a test piece for evaluating the performance as a hot melt adhesive was prepared.

Comparative Examples 1 to 3 Various hot melt adhesive compositions (compounds) were prepared in the same manner as in Example 1 except that the composition of the tackifying resin was changed as shown in Table 1 in Example 1. A test piece was also prepared in the same manner.

<Various Performance Test Methods> The respective compounds and test pieces obtained in the respective Examples and Comparative Examples were evaluated for performance as a hot melt adhesive as follows.

1 Heating stability 50 g of the sample compound was placed in a 100 cc stainless beaker and left in a circulating air dryer at 200 ° C. for 24 hours,
The degree of coloring and skinning was visually observed. ◯ means no coloring or skinning, and x means coloring or skinning.

2 Odor At 180 ° C., the degree of odor felt when the sample compound was mixed was expressed. ○ means no irritating odor, and × means irritating odor.

3 Normal temperature and high temperature adhesive strength An aluminum foil is further placed on the adhesive coated surface of the test piece obtained by the above method, the temperature is 180 ° C., the pressure is 1.5 kg / cm ² ,
Heat sealing under the condition of holding time of 1 second, using a universal tensile tester, room temperature is 20 ° C, high temperature is 60 ° C,
180 ° peel strength under conditions of 300 mm / min (g / 2
5 mm) was measured.

The test results are shown in Table 2.

Claims (3)

[Claims] 1. A hot-melt adhesive composition containing an ethylene copolymer, a wax and a tackifying resin as main components, wherein the tackifying resin has a softening point of 155 to 200.
C. and (A) reaction product of rosin phenol resin and metal compound, (B) reaction product of rosin phenol resin and polyhydric alcohol, and (C) rosin phenol resin and polyhydric alcohol and metal A hot melt adhesive composition, which is at least two kinds or (C) selected from a reaction product with a compound. 2. The hot melt adhesive composition according to claim 1, wherein the metal compound is a zinc compound. 3. The hot melt adhesive composition according to claim 1, which further contains rosin esters as the tackifying resin.