DE1960467A1 - Hot melt adhesive - Google Patents

Description

PATENT LAWYERS ^M

DIPL.-INQ. F. THIELEKE __ _{FR | C | <} . DR.-INQ. R. DDRINQ DIPL.-PHYS. DR. J. FRICKE

BRAUNSCHWEIG. MUNICH

Continental Can Company, Inc., 633 Third Avenue, Mew York 17 , NY / USA

"Hot melt adhesive"

The invention relates in particular to a hot-melt adhesive for tying fibrous sheet-like materials such as paper, regenerated cellulose, textile fabrics or like

In hot melt adhesives, the connection is formed as opposed to .Bildung ύοώ bridges or other chemical reactions by simple cooling. Before heating, the adhesives consist of thermoplastic substances. The use of hot melt adhesives is advantageous because they create the desired connections at high speeds and because no volatile substances need to be evaporated before the connection is made.

A Deicanntes method, n; jch the hot-melt adhesive mass can be applied to the respective substrate the so-called "hot melt extrusion process" The thermoplastic adhesive is the first process

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melted. After that, the molten material is passed through a Shape extruded to form a strip or film melted Material, which is then applied to the substrate will. In another "known method of applying the bite-melting adhesive is an application wheel or a Application roller used, to which the molten material is fed from a suitable storage container. With these Solvent costs are avoided. Much greater cost savings, however, result from the time savings which are achieved as a result of the short time between application and solidification of the hot-melt adhesives.

Hot melt adhesives are for the production of paperboard or Cardboard containers, such as cardboard cans with metal ends, folding boxes, Corrugated cardboard boxes and fiber drums, of great importance. In the manufacture of these containers, the fuselage is first converted into a square or ßohrform. After that will be certain edges of the cardboard blank from which the fuselage is made is brought into an overlapping position. A tight connection is created in that the previously with an order melted hot melt adhesive provided overlapped edges are pressed together. This work can be done by suitable collaborators Rolls or the like. Executed, which in addition depending on the requirements when making the adhesive connection can be cooled or heated.

Hot-melt adhesive compounds for cardboard containers have to have high binding forces

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ensure, especially under harsh conditions, such as Shock, high humidity, pressure and extreme temperatures, to which the containers "may be exposed during transport and storage. The! specialist world is constantly on the lookout for Hot-melt adhesive compositions which have better properties for use under the conditions mentioned.

The present invention provides a heat sealant having such improved application properties. It is according to the invention as a mixture of about 50 "to 40 percent by weight Ethylene-yinylacetate copolymer, about 20 to 30 weight percent a direrized resin acid, about 20 to 30 percent by weight of a chlorinated terphenyl and about 8 to 20 percent by weight composed of a hydrocarbon wax.

The hot melt adhesive composed according to the invention has Above-average binding properties and is within a very wide ambient temperature range compared to | Hate and humidity resistant.

The ethylene-vinyl acetate copolymer used for the hot-melt adhesive formed according to the invention must contain 10 to 25% of the copolymer weight of polymerized vinyl acetate. Adhesive gauges with an ethylene-vinyl acetate copolymer containing more than 28 percent by weight of polymerized vinyl acetate are found to be soft and have a decreasing consistency.

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compatibility with wax and poorer printing properties on. The use of an ethylene-vinyl acetate copolymer with less than 10 percent by weight copolymerized vinyl acetate leads to hot melt adhesives with low elasticity and inadequate sealing properties. In the case of the invention formed hot melt adhesive, the best results are achieved when the ethylene-vinyl acetate copolymer about 15 to Contains 20 weight percent copolymerized vinyl acetate.

Me used for the hot melt adhesive formed according to the invention Ethylene-vinyl acetate copolymers generally have a melt index in the range between 50 to 500 grams / 10 minutes (determined according to the ASIM method B-1238-57 T). A'tbylene-yinylacetate copolymers with a melt index above 500 have a molecular weight that is too low, in order to be able to be used for the hot-melt adhesive tape designed according to the invention. Purely trained according to the invention Hot melt adhesive preferably usable ethylene vinyl acetate Copolymers have a melt index in the range between 100 and 200.

Ethylene-vinyl acetate Copolyraerbarze that for the invention trained hot melt adhesive can be used, are commercially available. An example is the ethylene-vinyl acetate copolymer resin which is available under the designation "ELVAX 420" from E.J. duPont Company and has the following physical properties:

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Melt Index (ASTM D-1238) 125-175

^σ / ο vinyl acetate 18-20

Intrinsic viscosity at 30 ⁰ G. 0.54

Density at 23 ° C 0.937 - 0.940 '

Softening Point (ASTM E-28) 100 ⁰ G.

The chlorinated terphenyls which can be used for the hot-melt adhesive formed according to the invention are solid resins which contain about 50 to 70 percent by weight of chemically bound chlorine. Particular preference in the assembly according to the invention formed hot adhesive enjoy chlorinated terphenyls in a state of solid resins, with e.twa 58 to 68 percent by weight • chlorine content and softening points in the range between 95-160 ⁰ C.

Chlorinated terphenyls for the composition of the hot melt adhesive formed according to the invention are commercially available. An example of a commercially available chlorinated terphenyl which can be used for the hot melt adhesive formed according to the invention is the under the name "aROCHLOR 5460" from Monsanto Chemical Company. This product is a solid resinous material with the following physical Characteristics:

% Chlorine. 58.5 to 60.6

Degree of acidity (mg KOH / g raax) 0.05

Softening point ⁰ C (ASTM E-28) 98-105

Density at 25 ⁰ C 1.670

Distillation range ⁰ G (ASTM D-20) 280 - 335

(5 mm Hg). _ ₆ _

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The hydrocarbon waxes which can be used for the production of the inventively embodied hot adhesive have, in the range between 65 to ⁰ C 12Q lying melting points. They include paraffin and microcrystalline waxes, synthetic waxes, and mixtures thereof. Paraffin wax is a mixture of solid hydrocarbons that is obtained by fractional overhead distillation "in the distillation of petroleum. After cleaning, the paraffin wax contains hydrocarbons that fall under the following formula:

^G 23 ^H 48 ~ ^C 35 ^H 72.

This paraffin wax is a nearly colorless, hard and transparent material whose melting point is usually from 51 to 73 ⁰ C. Microcrystalline wax is obtained from the non-distillable residues of the fractional distillation of petroleum. It differs from paraffin wax in that it has hydrocarbon branches of higher molecular weight. It is much more plastic than paraffin wax and the melting point is usually between 65 and 92 ^° G.

For the production of the hot-melt adhesive mass formed according to the invention, a hydrocarbon wax can preferably be used which is obtained as a synthetic wax and the hydrogenation of carbon monoxide by the Pischer-Tropsch process. In waxes of this type, the melting point is between 81 and 103 ^° C. An example of a commercially available hydrocarbon wax produced by the Fischer-Tropsch process

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is the one available under the name "Paraflint RG-" Product of Moore and Munger Inc. This product has the following properties:

Melting point 153 ° C

Freezing point 95 C

Needle penetration hei 23 ⁰ C 1.5

Density at 23 ⁰ C. 0 * 945

Viscosity hei 120 ⁰ C 9.5 centipoise

% Oil content 0.5 (j

Acid number Ni 1.

The dimerized resin or colophonic acids used for the production of the hot-melt adhesive composition formed according to the invention have, as is assumed, the following structural formula:

^{cc> 6w}

Dimerized resin or colophonic acids, which according to the invention formed hot melt adhesive can be used, are ready-made commercially available. One such product is

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under the name "Dpolymerx resin" from Hercules Inc. available product. It has the following physical properties?

Softening point (ASTM ring and ball) 141 ⁰ C acid number 135

Saponification Number 145

Density at 20 ⁰ C 1.069.

During the production of the hot melt adhesive formed according to the invention it is a critical aspect of the invention that the composition be about 50 to 40 percent by weight Ethylene-vinyl acetate copolymer and about 20 to 30 percent by weight Contains dimerized resin or colophonic acid. If the proportion of ethylene-vinyl acetate copolymer and dimerized Resin or colophonic acid below the specified range is, then result in hot melt adhesives, their flexibility behavior and tensile properties with regard to the Pressure setting properties required for the practical conditions of use are unacceptable, i.e. not permitted. if the materials mentioned, however, are used in proportions above the specified limits, then hot melt adhesives with too poor viscosity and poor flow properties result in the most favorable resistance values to achieve against moisture on the cardboard base.

The hot-melt adhesive composition composed according to the invention must

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at least 8 percent by weight, generally between 8 and 20 percent by weight, Contain hydrocarbon wax to achieve acceptable vapor diffusion properties.

The chlorinated terpbenyl is added to the blend composition as a compatibility agent. It should be in a crowd of at least 20 percent by weight, generally in the proportion of 20 Ms 30 percent by weight, "can be added to get out of the Ethylene-Yinylacetat-Copolymer, the dimerized resin resp. Colphonic acid and the hydrocarbon wax are homogeneous To be able to generate mixture.

The compositions formed according to the invention are homogeneous mixtures which can be produced by processing the individual components in conventional mixers. For this purpose, jacketed kneader, or RoIlmiecher JPlügelradmiscber may serve, in which the polymers are incorporated by extrusion or flowing at temperatures between 100 to 200 ⁰ C. I.

For application to a paper would be subject such as fuselage cardboard, the heat-adhesive composition is heated to a temperature in the range 175 to 200 ⁰ G, and applied to one of the two surfaces to be joined. The thickness in which the film of the hot-melt adhesive is applied can be in the range between 39 and 50.5 grams per square meter.

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The hot melt adhesives composed according to the invention can contain numerous additives, e.g. fillers, organic and inorganic pigments and antioxidants. Such additives are well known and can be of the hot melt adhesive composed according to the invention in amounts which are known to the person skilled in the art are common, can be added without impairing the bonding properties of the hot melt adhesive. Examples of such Additives are: butylated hydroxytoluene, 2,2-methylene-bis (4-methyl, 6-textbutyl) phenyl, aluminum powder, kaolin ", titanium dioxide and the like.

The following example serves to further explain the Invention, but without limiting it in any way.

A hot melt adhesive consisting of the following was prepared Ingredients in the stated proportions composed:

Ethylene Yinylacetate

Copolymer (ELVAX 420) 33.3 $

Dimerized resin acid

(DYMEREX RESIN - 25.0 «/)

Chlorinated terphenyl

(AROCHLOR 5460) 25.0 ^ -

Hydrocarbon wax

(PARAi ¹ LINT RG) 16..7 #.

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Manufacture was initially a mixture of wax and chlorinated Kohlenwasserst off lerphenyl in a vessel equipped with a slow mixer, heated to 120 ⁰ C. Mixing was continued for 30 minutes until a bubble-free solution resulted. The dimerized resin acid was then added to this mixture and the temperature is raised in the boiler to 150 ⁰ C. The geroish was processed by the mixer at this temperature until the dimerized resin acid was broken up and dissolved.

The ethylene-vinyl acetate copolymer was then added to the mixture containing the dissolved rosin acid. The mixture was then stirred again for a period of 30 minutes in order to thoroughly mix all materials. The homogeneous mixture was then poured into the 3 orm of bars by pouring the molten mixture into pans with a tetrafluoroethylene coating and allowing it to solidify by cooling A

became. The result was a hot-melt adhesive mass of one 1M solid homogeneous mixture with the following properties:

Brookfield viscosity (20 BPM) centipoise

19O ⁰ C 1350

180 ⁰ C 1720

170 ⁰ C 2200

160 ⁰ C 2900

150 ° C 3700

HO ⁰ C 4000

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Softening point (ring and ball) 1O5 ° C

Specific heat 0.5 kcal / kg ° G

Thermal conductivity 0.496 kcal / mb ⁰ O

Flash point (after Cleveland

open cup) 268 ° C

moisture vapor diffusion rate in (grams / 645.16 cm / 24 b
"at 37.4 ⁰ C and 95 $ relative humidity" in a 1 mm thick Piim). 0.72 to 0.74.

™ The adhesive properties of this hot melt adhesive was through tried the following attempts:

The first attempt was the tear attempt. For this purpose, a sample of 21 kg Kraft paper, in strips of 2.54 x 15.24 cm size cut was used. A strip was on one side with a 2 mm thick layer of the hot hot melt adhesive. The order had a length of 508 cm and a width of 2.54 cm. It became a second one ti * paper strips placed. The sample thus obtained consisted of two strips of paper running along their contact surface

ρ
an area of 12.9 cm in size were connected to each other. To determine the adhesive properties, the free ends of the sample or the paper strips were grasped and slowly bent apart in the opposite direction at right angles to the adhesive bond. A tear-resistant bond is present if the Kraft paper yields in this sample, but not the bond. The experiment was carried out both at room temperature and at a temperature of -32 C.

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guided. The latter temperature was chosen to detect brittleness at the lowest temperature that the bond could be exposed to.

The second test was performed as a peel creep test. A two-inch lap joint was used in this experiment 2.54 x 15.24 cm strips of 21 kg kraft paper manufactured. The sample was on an area of

2
12.9 cm glued, the thickness of the glue application was 1 to 2 mm. The strip was hung at one end for half an hour in an oven at 59.4 ° C. and a weight of 300 g was hung from the other strip. There must be no sign of dissolution of the two papers if the sample is to have successfully passed the test.

The hot melt adhesive in the composition given in the example was applied to the 21 kg kraft paper and subjected to the two tests mentioned. In the hot test, a good tear resistance was found both at room temperature and at -32 ⁰ C.

In the creep test, after half an hour at 59.4 ° 0, no sign of detachment could be found.

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Claims (5)

-H- Claims Hot-melt adhesive in the form of a homogeneous mixture, characterized by the following composition ι a) about 30 to 40 percent by weight of an ethylene-yinylacetate copolymer b) about 20 to 30 percent by weight of dimerized resin or resin. Rosin acid c) about 20 to 30 weight percent chlorinated terphenyl d) about 8 to 20 weight percent hydrocarbon wax. 2. Adhesive composition according to claim 1, characterized in that the proportion of the ethylene-yinylacetate copolymer is between 15 to 25 percent by weight. 3. Adhesive composition according to claim 1, characterized in that the chlorine content of the chlorinated terphenyl is 58 to 68 ° /> . 4. Adhesive composition according to claim 1, characterized in that the hydrocarbon wax is a synthetic one Wax with a melting point between 81 and 103 ° C is provided by the hydrogenation of carbon monoxide is obtained according to the IPischer-Tropsch-Yerfahren. 5. Laminated body, thereby marked, that it consists essentially of paper documents that - Are connected by means of an adhesive according to claim 1. 009837/1871 BAD ORSGiHAL