JPS5818399B2 - hot melt materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hot melt adhesive or coating agent comprising a mixture of an ethylene-vinyl acetate copolymer (hereinafter referred to as EVA) as a base and a petroleum resin as a tackifying agent.

Conventionally, compositions made by mixing polyolefins and rosin or rosin derivatives, and optionally waxes, fillers, plasticizers, etc., have been used as hot melt adhesives or coatings for woodworking, shoemaking, bagmaking, and bookbinding. It is widely used in fields such as

This hot melt adhesive or coating agent has a solid content of 1001%.
Therefore, unlike solvent-based adhesives, there is no risk of fire, poisoning, or air pollution, and the ceratemperature time is short, so it has features such as mechanization and labor saving, so it is suitable for the recent demands for pollution-free adhesives.
Coupled with the growth in personnel costs, demand is rapidly increasing.

EVA is the most widely used base material for hot melt compositions due to its excellent flexibility and rigidity. Mixed with waxes.

The properties that a tackifying agent should have are excellent compatibility with the substrate, an appropriate softening point and molecular weight that do not cause blocking and do not increase melt viscosity. Or its derivatives have been awarded prizes.

However, since these are natural products, their supply is unstable, and especially in recent years, the price of rosin has increased sharply, so petroleum resins or coumaron-indene resins are used as substitutes.

Petroleum resins currently used as tackifiers for EVA have a boiling point of 145 to 280 degrees, which is obtained by naphtha decomposition, in order to have a softening point that does not cause blocking, for example in JP-A-48-47539. The amount of C fraction used must be increased, resulting in poor compatibility with EVA.

In addition, in JP-A-48-60738, which uses a maleic anhydride modified product of this resin, the molecular weight is high and the compatibility is poor, and the color and odor are poor, making it impractical.

In JP-A-48-79244, which uses hydrogenated petroleum resin, the hue and heat resistance are superior to rosin and its derivatives, but the adhesive strength and compatibility with EVA are inferior to rosin, and when considered together with the price. It is not worth using hydrogenated petroleum resin.

Furthermore, since JP-A-49-47-438 contains cyclopentadiene, it has extremely poor thermal stability and has the drawback of producing a strong odor when heated.

・The inventors have determined that the boiling point obtained in naphtha cracking is 20
Any fraction within ~80°C (hereinafter referred to as C5 fraction),
As a result of various studies on petroleum resins obtained by copolymerizing any fraction (hereinafter referred to as C9 fraction) with a boiling point of 150 to 250 °C obtained in naphtha cracking, we found that cyclopentadiene (hereinafter referred to as The present invention was made based on the finding that the content of dicyclopentadiene (hereinafter referred to as CPD) and dicyclopentadiene (hereinafter referred to as DCPD) greatly affects the compatibility with EVA.

The present invention involves heating the C6 fraction to 80 to 120°C and trimerizing the CPD in the C5 fraction to form DCPD, or adding maleic anhydride to the C5 fraction and carrying out the Dales-Alder reaction.
CPD in 5 fractions is 3,6-nindomethylene 2,3'
- After adjusting the content of CPD in the C5 fraction to 2 to 7% by weight and substantially 0% by weight of DCPD by converting it into 6-titrahydrocisphthalic anhydride and then removing it, this distillate is This mixture is mixed with a Friedel-Crafts type catalyst such as boron trifluoride or its ether complex, phenol complex, aluminum chloride, etc. in a weight ratio of 2:1 to 1:4. Add .0% by weight,
After reacting at a reaction temperature of 0 to 40 DEG C. for 12 to 5 hours, the catalyst is decomposed and removed with an aqueous alkali solution, and unreacted fractions and low polymers are further removed by distillation to obtain a petroleum resin.

This resin has a pale yellow color and a softening point of 40 to 150 DEG C., and is superior in compatibility with EVA and adhesiveness when used in an adhesive composition as compared to other petroleum resins.

50 to 150 parts of the petroleum resin thus obtained have a melt index of 15 to 450 and a vinyl acetate content of 10.
Add 100 parts of ~40% by weight EVA and uniformly melt and mix.

At this time, waxes, rosin derivatives, terpene resins, plasticizers, antioxidants, etc. are mixed as necessary to obtain a hot melt composition.

Generally, various resins can be obtained from copolymers of C5 and C0 fractions depending on the ratio of C5 and C9 fractions.
If the content of CPD and DCPD in the fraction is high, the molecular weight distribution of the resulting resin will be on the high molecular weight side, resulting in poor compatibility with EVA and poor heat resistance.

Moreover, if the content of CPD is low, the softening point will be low and blocking will easily occur.

To prevent this, it is sufficient to use a large amount of the aromatic C9 fraction, but as the amount of aromatics increases in the resin molecule, the compatibility with EVA deteriorates.

Therefore, in the present invention, after the C5 fraction is heat-treated, the cyclopentadiene content is adjusted to 2 to 7% by weight by topping it to remove it or adding maleic acid to it and filtering it to remove it. shall be.

Furthermore, the ratio of the C5 fraction to the C9 fraction is such that if the C9 fraction is small, the softening point will be low and blocking will occur easily, and the number of aromatic nuclei in the resin molecules will be small (as a result, the adhesive strength will be poor). come.

If the C9 fraction increases, the compatibility with EVA will be poor, making it undesirable as a tackifier.

For this reason, the weight ratio of the C5 fraction to the C9 fraction needs to be 2:1 to 1:4.

The EVA used in the present invention has a melt index of 15 to
450 and having a vinyl acetate content of 10 to 40% by weight are preferred, and it is also possible to mix this with an acrylic acid copolymer, polyamide resin, polyester resin, etc. with EVA.

In addition, the waxes mixed with EV, A, and petroleum resin are
Mineral waxes such as paraffin wax, polyethylene wax, polypropylene wax, and microcrystalline wax are suitable, but it is also possible to use vegetable waxes.

By changing the mixing ratio of the petroleum resin and EVA and/or waxes according to the present invention, it can be applied to various applications. However, when the amount of petroleum resin is increased, the melt viscosity of EVA decreases and the initial adhesive strength increases. The adhesive strength decreases, and if the amount of petroleum resin is reduced, the adhesive strength of EVA increases, but the melt viscosity increases, resulting in poor workability.

Therefore, for 100 parts by weight of EVA, 50 to 1 part of petroleum resin
By mixing at a ratio of 50 parts by weight, a hot melt composition with excellent adhesive strength can be obtained.

Next, reference examples related to the production of petroleum resin used in the present invention and examples of the present invention will be shown.

(% is weight percentage) Reference Example 1 A fraction with a boiling point of 20 to 80°C obtained in naphtha cracking containing 14.8% isoprene, 8.3% piperylene, and 12.6% cyclopentadiene was divided into 4 parts and 100% ℃
Heat treatment was performed for 30 minutes, 2 hours, 6 hours, and 10 hours at a cyclopentadiene content of 8.3%, 6.
After adjusting to 8%, 2.2% and 1.6%, the fractions from which dicyclopentadiene was removed by distillation were converted to C5-
1, C5-2, C5-3 and C5-4.

Each of these is divided into 6 parts, and the fraction with a boiling point of 150 to 250 °C obtained in naphtha cracking containing 378% of styrene, vinyltoluene, and indenes is divided into 3:1.2:1.1:1.1. :3.1:4 and 1:5
500 g of the mixture was put into a No. 11 four-bottle flask equipped with a stirring bar, thermometer, condenser, and dropping funnel, and while keeping the temperature at 20°C, gradually added 4 g of the phenol complex salt of boron trifluoride. Add dropwise and react with stirring for 3 hours.

Next, wash with the same amount of 1% caustic soda aqueous solution as the reaction solution,
Decatalyze.

Furthermore, it is washed twice with the same amount of water as above to remove the catalyst decomposition product and alkali content (the reaction product is blown with steam at 200°C to remove unreacted products and low polymers to obtain petroleum resin. .

The softening point of each petroleum resin was measured and the results are shown in the table.

Reference Example 2 A fraction obtained by heat-treating a fraction with a boiling point of 25 to 75°C obtained in naphtha decomposition to adjust to 3.5% cyclopentadiene and removing dicyclopentadiene (referred to as C5-5)
(Contains 13.5% isoprene and 75% piperylene)
and boiling point 150-220°C obtained in naphtha cracking
fractions (styrene, vinyltoluene and indenes 42
%) in a ratio of 1:3, boron trifluoride was blown into this 500 g at 20° C. and reacted for 3 hours, and a petroleum resin was obtained in the same manner as in Reference Example ①.

The softening point of this petroleum resin was measured and the results are shown in the table.

Reference Example 3 A fraction with a boiling point of 25 to 80°C obtained in naphtha decomposition is heated to adjust the concentration to 4.2% cyclopentadiene and remove dicyclopentadiene (referred to as C5-6)
(containing 15.2% isoprene and 8.1% piperylene) and a boiling point of 150-170° obtained in naphtha cracking
C fraction (styrene, *- containing vinyltoluene and indenes 36.1%) was mixed in a ratio of 1:2, 2.02 g of aluminum trichloride was added dropwise to 500 g of the mixture, and the mixture was heated at 10°C. The reaction was carried out for 2 hours, and a petroleum resin was obtained in the same manner as in Reference Example 1.

The softening point of this petroleum resin was measured and the results are shown in the table.

Examples 1 to 10 and Comparative Examples 1 to 17 10 each of the petroleum resins obtained in Reference Examples 1 to 3
After melting 0g and 40v of paraffin wax (melting point below 145) in a stainless steel beaker, gradually added ethylene-vinyl acetate copolymer (Evaflex #220; manufactured by Mitsui Polychemical Co., Ltd. 00g) and heated at 160°C. Mix for 2 hours to obtain a hot melt composition.

In addition, a hot melt composition is obtained in the same manner as above at ℃ using rosin instead of petroleum resin.

The cloud point and adhesive strength of each composition were measured and the results are shown in the table.

Test method (1) Softening point: Based on the ring and ball method.

(2) Clouding point: Take the hot melt product into a test tube,
After heating to °C, let it cool and measure the degree of cloudiness.

(3) Adhesive crab Place aluminum foil on a stainless steel plate adjusted to a surface temperature of 150°C, and apply 10ml of hot melt product melted at 170°C onto it.

This was compressed and bonded using a heat sealer using aluminum foil as an adherend at 150° C. and a pressure of 1 kg/crA for 1 second.

After adhesion, the test piece was left at 20°C and 65% RH for 24 hours, and the test piece was cut into 25 x 300 mm. This test piece was subjected to a tensile test using Tensilon at 180 degrees and 100 mm/mi7+, and the results are shown in the table. .

Claims (1)

[Claims] 1 Any fraction with a boiling point of 20 to 80°C obtained in naphtha decomposition is processed by a conventional method to reduce the cyclopentadiene content to 2 to 7% by weight and the dicyclopentadiene content to substantially 0. After adjusting to % by weight, this and any fraction with a boiling point of 150 to 250 °C obtained in naphtha cracking are mixed in a weight ratio of 2:1 to 1:4, and this is mixed with a fraction by weight in the presence of a Friedel-Crafts type catalyst. A hot melt composition obtained by mixing the petroleum resin produced by the reaction described below with an ethylene-vinyl acetate copolymer.