DD222322A1 - MELT ADHESIVE COMPOUNDS WITH VARIABLE OPEN TIME - Google Patents

Abstract

Hot melt adhesive compound with variable open time for adhesive bonds at nonstationary sites, such as those used in the hand and home improvement area in embroidery form using applicator guns. The finished-formulated hotmelt adhesive is prepared by compounding from 25 to 70% by weight of ethylene-vinyl acetate copolymers, from 5 to 25% by weight of a terminal-carboxylated alpha-methylstyrene oligomer, from 5 to 35% by weight of a low molecular weight polystyrene and from 0.1 to 5% by weight .-% of an anodized polyethylene wax. The setting of the open time of the hotmelt adhesive is achieved by the compounding of low molecular weight polymers of the polystyrene which, by means of defined solidification ranges and melt viscosities, ensure an adjustment of the open time for the hot melt adhesive compounds. The developed hotmelt adhesive is particularly used as a mounting adhesive in the woodworking and metalworking industry, where the composites of plastic, elasto, metal, wood and siliceous materials can bond with one another and with one another.

Description

VSB Leuna-Werke Leuna,

"Walter Ulbricht"

LP 8393

Title of the invention. ',,

Hot melt adhesive compounds with variable open time

Field of application of the invention

The invention relates to hotmelt adhesive compounds which, due to their longer processing time, are used especially for assemblies in the assembly area at non-stationary places of use, such as those used in hand and home use, preferably with hotmelt adhesive sticks.

Characteristic of the known technical solutions

Hot melt adhesives (Hot IiELTS) are solvent-free, thermoplastic adhesive compounds which are solid at room temperature and are liquefied to wet the adhesive surfaces by the supply of heat energy and then solidified by cooling.

Λ O O SC / l

with binders.This distinguishes two basic polymer groups from HOT BiISLTS,

- Thermoplastic Elastomers' V-

-Thermoplastic resins or plastics. , y

Thermoplastic elastomers include the ethylene-vinyl acetate copolymers, ethylene-ethyl acrylate copolymers, polystyrene-butadiene-polystyrene block polymers, polyethylene, polypropylene, and butyl isobutyl and isoprene rubber types, and ethylene-propylene rubber. Thermoplastic; Synthetic resins are, for example, polyvinyl acetate ^: and their copolymers, saturated polyester and copolyesters, polyamides and polyurethanes (Adhäsion, (1977) Sonderdok. P. 65-68).

'. '5

The basic polymers mentioned can not usually be used alone in many application areas as HOT MELTS. By base polymer modification with certain additives, HOT MELTS obtain the desired specific properties. V · '..'. ,

Known HOT MELTS are predominantly binary or ternary / mixtures of substances, which consist predominantly of base polymer and / or resin and / or waxes, wherein in special cases plasticizing agents, fillers and stabilizers have properties which improve the properties (DE-OS 1 265 327, GB-PS 2 027 721, JP-PS 66 69 706).

The most important properties of each HOT MELTS are melt viscosity, processing temperature, open time, temperature and aging resistance, flexibility, adhesion and cohesion.

A particularly important hot melt adhesive property for the potential user is, in addition to good cohesive and adhesive behavior, the "open time" of the HOT 1! ELTS. The open time (given in seconds / at corresponding processing temperature) of the HOT IvIELTS results from the

Period of time in which after the Klebeäuftrag complete wetting and bonding is still possible. Influence on the open time, the HOT LiSLTS have, for example, the polymer composition, application thickness, room temperature, substrate temperature and thermal conductivity of the substrate (DD-PS 150 623). For example, to regulate the open time of a hot melt adhesive, this can be done via the softening temperature of the resin. It is the relationship, the higher the softening temperature of the resin, the smaller the resulting open time of the HOT MELTS. , '

In DD-PS 150 623, the production of hot melt adhesive, low softening temperature, lower. Melt viscosity and extended open time using already industrially manufactured base materials (ethylene-vinyl acetate copolymer, rosin, wax) described. Low melt viscosities, however, degrade the melting, mixing and handling properties (DS-OS 1 594 676).

The use of rosins in HOT IIIELTS has the disadvantage that the resins from natural sources are not unlimited, they are usually very expensive and economical only for specific applications.

The term "tackifying resin" is used on the adhesive sector to designate a material which upon addition to an adhesive composition promotes its adhesion to a substrate by improving its ability to wet the substrate. Suitable tackifying additives are, for example, copolymers of vinyltoluene and alpha-methylstyrene (DE-OS 2 907 941). The particular use of copolymer resins containing mainly styrene, vinyl toluene, alpha methyl styrene is limited by their unsatisfactory compatibility with the base polymers (DS-OS

2 417 934). , '; ;

The currently recognizable new trends in the hot melt sector are ". - the simultaneous use of two or more basic

, polymeric and. '..' .-. , .

the modification of the customary base polymers by grafting polymers, new backbone nacromolecules while reducing chemically oxidative reactions and at the same time saving stabilizers

- Simultaneous use of hydrocarbon and KbIophoniuniharzen. ; '.

Although the modification entails a product increase in itself, but it provides significantly improved property values (Coating 13/1980/7 172 - 130).

Aim of the invention; :.

The aim of the invention is the adjustability of the so-called open time for hot melt adhesive compounds, which is particularly in the assembly aid in the hand and 'DIY sector of great interest. , . · ....

Explanation of the essence of the invention

The object of the invention is the development of a hot melt adhesive compounds with variable open time, as in assembly work on nonstationary Einsatzorton in composites of materials such as plastic, Elaste, silicate materials and'Metalle with and among themselves, particularly im.Hand- and DIY are needed and preferably in the form of sticks use.

This object is achieved by melt adhesive compounds with variable open time based on thermoplastic. Elastomers, tackifying natural or synthetic resins, Yfachse and stabilizers dissolved, according to the invention, the compounds 25 to 70 Gev /.- SS. Ethylene-vinyl acetate copolymers having from 28 to 45% by weight of vinyl acetate, a melt index of 20 to 180 g / 10 min at 463 K and 2.16 kg and 5 to 25 wt .-% of a endgruppencarboxylierten alpha-Methylstyrenoligoineren with 'one molecular weight M _n 5QO'bis 800 and 5 to 35 wt .- # of a low molecular polystyrene having a molecular weight M of 1100 to 2500 and a nonuniformity U of 0.5 to 2.5 and 0.1 to 5.0 wt .- ^ an anoxidized polyethylene wax having an acid number of 14 to 18 mg KOH / g and a melt viscosity of 180 to 380 ta Pa · s included.

Due to their time-adjustable processing temperature range, the compounds are well suited for the hand and home improvement sector. The broad processing temperature range is measurable with the so-called "open time" ¹ , which results from the period of time in which sufficient wetting and bonding is still possible after the application, the problem of the compatibility of the compound constituents and the wetting of the substrates to be bonded The bonding over so-called Schmelsklebsticks sticks, which allow the handyman and do-it-yourselfer by means of a suitable hot-melt adhesive applicator gun a rational and economical order with favorable opening times of the Schmelsklebsto'ffcompounds is particularly favorable over the additives of the anoxidierten Poly.

embodiments

The characterization of the starting and end products is based on the following test methods;

TGL 20 996 ^ clay index (g / 10 min) at 463K

Rotational Viscosity Melt Viscosity at '473K 'Rheotest II, Measuring System H (πι Pas)

Heating Table Microscope Melting Point (K)

Brief description of the determination of open time

''. By means of a laminated adhesive film, two lines of linen corresponding to SGL 05 3274 (release strength) were applied after different times after adhesive application (0, 5, TO, -15, 20, 25, 30, 35, 40, 40). 45, 50 seconds). ' The test specimens were subjected to the determination of the release strength analogously to TGL. As open time, the time interval at which the release strength still reaches> 60 % of the initial release strength was selected.

Example 1 . _·:

Sine mixture of 45.2 Ma. -% of an ethylene-vinyl acetate copolymer having a Yinylacetatgehalt of 28.2 Ha " -% and a melt ex ex of 25 g / TO min at 463 K and 24.0 Ma .-% of a carbozylated alpha-Methylstyrenoligomer-en (CAIiS) were at Homogenized 438 K in a laboratory kneader. -%. low molecular weight polystyrene (! IPS) with an average molecular weight M. _fl 1100 to 2500 and 0;, 8 Ivia .-% of an anodized wax (. acid number 14 to 13 mg KOH / g) mixed and the entire mixture to, for optical Homogeneity processed. The resulting hot-melt adhesive, substance compound is characterized by a melt viscosity of 1.43 "10 m Pas.

The determination of the open time after the o. G. Specified a value of 20 seconds.

Examples 2 to 6:

The preparation of the hot melt adhesive compounds of Examples 2 to 6 and their characterization is carried out analogously to the procedure described in Example 1.

The following table lists the starting materials and the characterization of the resulting hotmelt adhesive compounds.

Sabelle: Composition and characterization of the melt adhesive compounds 1 to 6

at copolymers Vac. enamel CAHS- mol game proportion of salary index proportion of mass fo dg min resin S % 28.2 25 ^% 600 1 '45, 2 28.9 45 24: 750 2 45.2 33.4 125 19 750 3 56.2 31.7. 179 16 550 4 56.2 41.3 86 21 500 5 65.2 42.3 ^; 93 20 650. 6 65.2 23

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Table: Composition and characterization of hotmelt adhesive compounds 1 to 6>

at · HPS mol ΡΞ-7 / axle characterization Schmelzvis 10 ⁵ game Proportion of . mass open viscosity by. to ⁴ resin Time mPas  · # - 16-00 S 1,4 ^ to ⁴ 1 - 30 1600 · 0.8 20 2.64. ro ⁴ 2 35 2500 0.8 30 1.91. 10 ⁴ ' 3 · 27 1100 0.8 15 2.58. .4 22 1200 0.8 35. 1,90. 5 14 1750 0.8 50 3,59. β .10. 0.8. 30

Claims (1)

• invention claim Hot melt adhesive compounds with variable open time, based on thermoplastic elastomers, klebrigmachen- of natural or synthetic resins, waxes and stabilizers, characterized in that the compounds .25 to 70 weight '.-% ethylene-vinyl acetate copolymers with up to 45 wt -.% Vinyl acetate, a melt index of 20 to 180 g / 10 min at 463 K. and 2.16 kp and. , 5 to '25 Gew. - iS of a endgruppencarboxylierten alpha-Methylstyrenoligomeren with a molecular weight M 500 to , 800 and. - · 5 to 35% by weight of a low molecular weight polystyrene having a molecular weight M of 1100 to 2500 and a nonuniformity U of 0.5 to 2.5 and 0.1 to 5.0% by weight of an anodized polyhexylene wax having an acid number from 14 to 18 mg KOH / g and a melt viscosity of 180 to 380 mPas. · . . ' ..: