DE19528369A1 - Polymer-based adhesives, esp. for non-polar substrates - Google Patents

Abstract

Polymer-based adhesives are claimed, contg. 0.2-80 wt%(w.r.t. polymer) of oligopropene derivs. of formula (I), (II) or (III) (where n = 0-100; X = a gp.) with a mol. wt. of less than 300 contg. at least one copolymerisable olefinic double bond or a reactive H atom. Also claimed are substrates coated with these adhesives. Pref. the polymer has a Tg of -50 to+40 deg C and contains 1-65 wt% (I-III). Pref. polymer is obtd. by polymerisation of (a) 20-99.8 wt% 1-10C alkyl (meth)acrylate, vinyl 1-20C carboxylate, up to 20C vinylaromatic, unsatd. nitrile, vinyl halide, 1-10C alkyl vinyl ether and/or 2-8C aliphatic mono- or di-olefin as main monomer, (b) 0.2-80 wt% (I), (III) or unsatd. oligomer (II) and (c) 0-50 wt% other comonomers; or a mixt. of 50-99.8 wt% (a) and 0.2-50 wt% (c) is polymerised first and then reacted with oligomer (II) contg. a reactive H atom.

Description

The invention relates to adhesives based on a polymer, which ches from 0.2 to 80 wt .-%, based on the polymer, from oligo propene derivatives of the formula

or

exists, where n is an integer from 0 to 20 and X for a group with a molecular weight below 300 g / mol, which has at least one copolymerizable olefinic double bin tion or contains a reactive hydrogen atom.

Previously known adhesives show on non-polar substrates, ins especially on polyolefins, often only insufficient adhesion. So-called tackifiers are generally used to improve liability added. In R. Mülhaupt, Adhäsion 1993, 37, page 26-30 Oligopropene as a tackifier to improve the adhesion to un polar substrates recommended. The improvement in liability achieved is generally not sufficient, however. Furthermore the addition of oligoprene adversely affects cohesion, d. H. the internal cohesion of the bond.

The object of the present invention was therefore adhesives which also have good adhesion to non-polar substrates and Ver bonds with high cohesion result.  

Accordingly, the adhesives defined above have been found.

The adhesives according to the invention contain polymers which 0.2 to 80 wt .-%, based on the polymer from the oligopropene derivatives of the formula I, II or III exist, d. H. this covalent bound included. The oligopropene derivatives are as such knows. Their manufacture is e.g. B. in Mülhaupt, Adhäsion 1993, 37, Pages 26-30. The production of functionalized Oligopropenes are e.g. B. also known from DE-A-40 30 399. The Preparation of oligopropene derivatives of the formula III is e.g. B. from EP-A-268 214 known.

Preferred oligopropene derivatives of the formula I are those with n = 1 to n = 80 and particularly preferably with n = 2 to n = 50.

Since mixtures are generally used in the production of oligopropenes are obtained, n is an average for the C₃ units contained in the molecule.

In formula II, X represents a group with at least one preferably an olefinic double bond, so that the Oligopro Pen derivatives such as those of formula I are copolymerizable. Such groups are special

d. H. Acryloxy, acrylamide or vinyl ether groups.

R¹ in the formulas represents an H atom or a methyl group. R² stands for an aliphatic radical with 1 to 10 carbon atoms preferably for a C₁-C₄ alkyl group.

Alternatively, X in formula II stands for a group which has at least one contains at least one, preferably a reactive H atom, so that these oligopropene derivatives by reaction with a polymer, which groups reactive with this H atom, e.g. B. an iso Has cyanate, acid anhydride, are bound to the polymer can. The table below gives information about preferred ones Groups X and with these reactive groups in the polymer.  

X is preferably OH, NH₂ or NHR³, where R³ is one aliphatic radical of 1 to 20 carbon atoms, especially one C₁-C₄ alkyl radical.

The oligopropene derivatives are independent of the polymer Type of covalent attachment to 0.2 to 80 wt .-%, preferably 1 up to 65% by weight and particularly preferably 5 to 50% by weight on the polymer.

The polymer is intended for use as an adhesive preferably a glass transition temperature of -50 to +40, especially preferably from -40 to +20 and very particularly preferably from -40 to 0 ° C.

The glass transition temperature of the polymer can be adjusted according to the usual Methods such as differential thermal analysis or differential scanning Calorimetry (see e.g. ASTM 3418/82, so-called "midpoint temperature") determine.

The polymer is preferably a polymer, which by polymerizing ethylenically unsaturated Compounds (monomers) is produced.

In addition to the oligopropene derivatives, the polymer preferably contains so-called main monomers selected from C₁-C₂₀ alkyl (meth) acrylates, Vinyl esters of carboxylic acids containing up to 20 carbon atoms, Vinyl aromatics with up to 20 carbon atoms, ethylenically unsaturated Nitriles, vinyl halides, vinyl ethers of 1 to 10 carbon atoms ent holding alcohols, aliphatic hydrocarbons with 2 to 8 carbon atoms and 1 or 2 double bonds or mixtures of these Monomers.

To mention are z. B. (meth) acrylic acid alkyl ester with a C₁-C₁₀ alkyl radical, such as methyl methacrylate, methyl acrylate, n-butyl acrylate, ethyl acrylate and 2-ethylhexyl acrylate.  

In particular, mixtures of the (meth) acrylic acid alkyl esters suitable.

Vinyl esters of carboxylic acids with 1 to 20 carbon atoms are e.g. B. Vinyl laurate, stearate, vinyl propionate, vinyl versatic acid and vinyl acetate.

Suitable vinyl aromatic compounds are vinyl toluene, α- and p- Methylstyrene, α-butylstyrene, 4-n-butylstyrene, 4-n-decylstyrene and preferably styrene. Examples of nitriles are Acrylonitrile and methacrylonitrile.

The vinyl halides are substituted with chlorine, fluorine or bromine ethylenically unsaturated compounds, preferably vinyl chloride and Vinylidene chloride.

Examples of vinyl ethers include B. vinyl methyl ether or vinyl isobutyl ether. Vinyl ether of 1 to 4 carbon atoms is preferred keeping alcohols.

As hydrocarbons with 2 to 8 carbon atoms and two olefinic Double bonds are butadiene, isoprene and chloroprene.

In addition to these main monomers, other monomers, e.g. B. Hydro Monomers containing xyl groups, in particular C₁-C₁₀ hydroxy alkyl (meth) acrylates, (meth) acrylamide, ethylenically unsaturated Acids, especially carboxylic acids, such as (meth) acrylic acid or Itaconic acid, dicarboxylic acids and their anhydrides or half esters, e.g. B. maleic acid, fumaric acid and maleic anhydride in the polymer be included.

As needed, e.g. B. to connect oligopropene derivatives with right active hydrogen in X can e.g. B. also monomers with an iso cyanate group are used.

If necessary, the polymer can also contain crosslinking monomers with 2 or contain more than two double bonds as further monomers. Of the The content of the crosslinking monomers is in general if 0.05 to 5% by weight, based on the polymer, is at all desirable.

In the case of polymers that can be crosslinked by high-energy radiation there are also copolymerizable, ethylenically unsaturated photos initiators, e.g. B. acetophenone or benzophenone derivatives as white Tere monomers into consideration, such as. B. from EP-A-246 848 or DE-A-38 44 445 are known. In the case of their shared use their proportion generally 0.05 to 5, preferably 0.1 to 3  % By weight (the maximum possible proportion of the main monomer reduced accordingly).

Overall, the polymer z. B. composed as follows

• I) For copolymerizable oligopropene derivatives:
  • a) 20 to 99.8, preferably 35 to 99 and particularly preferably 50 to 95% by weight of main monomers
  • b) 0.2 to 80, preferably 1 to 65 and particularly preferably 5 to 50% by weight of copolymerizable oligopropene derivatives of the formula I, II or III
  • c) 0 to 30, preferably 0 to 20 and particularly preferably 0 to 10% by weight of further monomers
• II) In oligopropene derivatives of the formula II, which by Um settles with a reactive hydrogen atom of group X at the bottom are bound polymer, a polymer is preferably first made from the main monomers and other monomers. The other monomers contain monomers which are used for the Um setting with the reactive H atoms of group X are suitable (see above) in the desired amount. After the polymerization the reaction then takes place with the oligopropene derivatives Formula II, which contain a reactive H atom, so that the Desired amount of oligopropene, i.e. 0.2 to 80, preferably 1 to 65 and particularly preferably 5 to 50 wt .-%, based on the polymer contained in the polymer. The share of the main monomer preferably corresponds to that mentioned under I) ten.

The monomers can preferably be free radical or as far as possible can also be anionically polymerized. Both the radical as Anionic polymerization is also common methods and known to the expert.

The radical polymerization can e.g. B. in solution, e.g. B. one organic solvent (solution polymerization) in aqueous Dispersion (emulsion polymerization, suspension polymerization) or in bulk, d. H. essentially in the absence of water or organic solvents (bulk polymerization) leads.

The emulsion polymerization can e.g. B. discontinuously, with or without the use of seed latices, with presentation of all or individually ner components of the reaction mixture, or preferably below  partial submission and replenishment of the or individual stock parts of the reaction mixture, or according to the dosing process without Template.

The monomers can be used as usual in emulsion polymerization in the presence of a water-soluble initiator and an emul gators are polymerized at preferably 30 to 95 ° C.

Suitable initiators are e.g. B. sodium, potassium and ammonium persulfate, tert-butyl hydroperoxides, water-soluble azo bonds or redox initiators such as H₂O₂ / ascorbic acid.

As emulsifiers z. B. Alkaline salts of longer chain fat acids, alkyl sulfates, alkyl sulfonates, alkylated aryl sulfonates or alkylated biphenyl ether sulfonates. Furthermore come as Emulsifiers Reaction products of alkylene oxides, in particular Ethylene or propylene oxide with fatty alcohols, acids or Phenol, or alkylphenols into consideration.

In the case of aqueous secondary dispersions, the copolymer first by solution polymerization in an organic Solvent produced and then with the addition of salt formers, e.g. B. from ammonia to carboxylic acid groups Copolymers, in water without the use of an emulsifier or Dispersing aid dispersed. The organic solvent can be distilled off. The production of aqueous secondary dispersions is known to the skilled worker and z. B. in the DE-A-37 20 860.

To adjust the molecular weight in the Polymerisa tion controller can be used. Are suitable for. B. -SH containing Compounds such as mercaptoethanol, mercaptopropanol, thiophenol, Thioglycerin, thioglycolic acid ethyl ester, thioglycolic acid methyl esters and tert-dodecyl mercaptan.

The solids content of the polymer dispersions obtained is preferably 40 to 80, particularly preferably 45 to 75% by weight. High polymer solids can e.g. B. according to the method in German patent application P 4 307 683.1 or EP 37 923 are set.

A preferred polymerization method is solution poly merization. The solution polymerization can be continuous, dis continuously as a batch process or preferably semi-continuous be carried out in the feed process. In the latter In this case, part of the monomers is placed on the polymer  heated and the rest of the monomers continuously fed.

As a solvent for radical solution polymerization, see above as for any subsequent implementations in Solution z. B. alcohols such as i-butanol, i-propanol, aromatics such as toluene or xylene, ethers such as dioxane or tetrahydrofuran, Ke clays such as acetone or cyclohexanone or esters such as ethyl acetate or n-Butyl acetate can be used.

Preferred initiators are dibenzoyl peroxide and tert-butyl per pivalate, tert-butyl per-2-ethylhexanoate, tert-amyl-2-ethylhexyl peroxide, di-tert-butyl peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, dilauroyl peroxide, tert.-butyl peroxymaleinate, tert.- Butyl peroxybenzoate, dicumyl peroxide, didecanoyl peroxide, methyl ethyl ketone peroxide, 2,2'-azobis- (2,4-dimethylvaleronitrile), 2,2'-azobis (2,3-dimethylbutyronitrile) and 2,2'-azobisisobutyro to call nitrile.

In bulk polymerization, part of the bottom is generally submitted to the polymerization temperature door heated, after which the rest of the feed was continuously added leads.

The polymer is dependent on the polymer selected onsmethode in the form of an aqueous dispersion of the polymer, a Solution in an organic solvent or essentially preserved water and solvent free.

The polymers can be used as an adhesive in these forms the. If necessary, additives such as rheology aids medium, thickeners, tackifying resins, e.g. B. rosin, be added.

In the case of an aqueous dispersion or organic solution of the The water or organic solvent is added to polymers the application preferably largely removed so that only the dry polymer film remains.

The polymer is suitable for bonding a wide variety of sub strate z. B. made of wood, plastic, paper, metal, etc. Ins it is particularly suitable as a pressure sensitive adhesive.

The polymer is particularly preferred as a hot melt adhesive (i.e. essentially free of water and solvents), especially be preferably used as a hot melt pressure sensitive adhesive.  

Radiation-curable hot melt adhesives are particularly preferred substances or hotmelt adhesives that copolymer in the polymer based photoinitiators. Radiation-curable enamel adhesives are applied with ener after application to the substrate greedy light, e.g. B. UV light.

In particular, the polymer is also suitable as a hot melt pressure sensitive adhesive fabric for laminated film lamination.

The adhesives according to the invention show very good adhesion non-polar surfaces, e.g. B. to polyolefins such as polypropylene. she therefore do not require the addition of a tackifier for liability on non-polar surfaces.

In addition, the bonds obtained have a high internal Firmness (cohesion).

Examples I. Double bonded oligopropenes a) Manufacturing

Under an inert gas atmosphere, an initial charge consisting of 5% by weight of the monomer feed I and 5% by weight of the initiator feed II and 38 g of i-butanol was adjusted to a reaction temperature of 103 ° C. and polymerized for 10 minutes. Then the internal reaction temperature was raised to 118 ° C. and the two feeds started, the monomer feed I, consisting of the acrylic ester monomers, photoinitiator and the double bond-functionalized oligopropene, being fed in in 3.5 h and the initiator feed II in 4 h. After the feeds had ended, polymerization was continued for 3 hours at 118 ° C. and the solvent and volatile constituents were distilled off in vacuo.
Inlet I:
323 g of n-butyl acrylate
19 g acrylic acid
38 g oligopropene
1.3 g photo initiator
Inlet II:
0.15 g tertiary butyl peroctoate
29.1 g iso-butanol

The copolymer compositions are shown in Table 1 men (in parts by weight).  

b) Examination

The substrates to be bonded were OPP films of the layer 30 µm thick (OPP = oriented polypropylene).

The adhesives were applied as a melt on a film with a layer thickness of 20 µm. The samples were irradiated with a throughput speed of 10, 30 and 50 m / min under the UV lamp (120 W / cm), then a second one Laminated with OPP film.

Then the bond with a calender roll (6.5 bar / 4800 N) at 150 N / cm and 5 m / min continuous speed rolled.

The strength of the composites was tested in a 180 ° peel test tested with a take-off speed of 100 m / min (result nisse in table 2).

Table 2

Peel strengths

II. Oligopropenes with an OH, NHR group a) Manufacturing

The polymerization was carried out as under I, with feed I taking place of the copolymerizable oligopropene derivative contained functional monomers. Then 150 g of the polymer obtained at an internal temperature of 70 ° C. 2 Hours with the OH functionalized oligopropene in Ge currently treated by toluenesulfonic acid.

Table 3

Composition (in parts by weight)

b) Examination

The polymers obtained were made on a polyester film Polyethylene terephthalate (40 µm thickness) applied and at a throughput speed of 5 and 10 m / min with a Irradiance of 120 W / cm irradiated.

The self-adhesive film thus obtained was then applied covered with a polyethylene base, 24 h at room temperature stored in a 180 ° peel test with a trigger speed tested to 300 mm / min.  

Table 4

Peel strengths

Claims (15)

1. Adhesives based on a polymer which contain 0.2 to 80% by weight, based on the polymer, of oligopropene derivatives of the formula or exists, where n is an integer from 0 to 100 and X represents a group with a molecular weight below 300 g / mol, which contains at least one copolymerizable olefinic double bond or a reactive hydrogen atom. 2. Adhesives according to claim 1, wherein the polymer 1 to Contains 65 wt .-% of the oligopropene derivatives. 3. Adhesives according to claim 1 or 2, wherein the glass transition temperature of the polymer is from -50 to + 40 ° C. 4. Adhesives according to one of claims 1 to 3, wherein the poly mer by polymerization of a monomer mixture

• a) 20 to 99.8% by weight of main monomers selected from
  C₁-C₁₀-alkyl (meth) acrylates, vinyl esters of up to 20 C-atoms containing carboxylic acids, vinyl aromatics with up to 20 C-atoms, ethylenically unsaturated nitriles, vinyl halides, vinyl ethers of 1 to 10 C-atoms and alcohols and aliphatic hydrocarbons with 2 to 8 carbon atoms and 1 or 2 double bonds
• b) 0.2 to 80 wt .-% oligopropene derivatives of the formula I, III or ethylenically unsaturated oligopropene derivatives of the formula II and
• c) 0 to 50% by weight of further monomers

is obtained and the weight data on the monomer are mixed. 5. Adhesives according to any one of claims 1 to 3, wherein for the preparation of the polymer, a mixture of monomers is first made

• a) 50 to 99.8 wt .-% of the above main monomers and
• b) 0.2 to 50% by weight of further monomers,

is polymerized, and then a polymer-analogous order setting with oligopropene derivatives of the formula II, which contain reactive hydrogen atom takes place. 6. Adhesives according to one of claims 1 to 5, which we free of organic solvents and water are. 7. Adhesives according to one of claims 1 to 6, which by high-energy radiation can be networked. 8. Adhesives according to one of claims 1 to 7, wherein the poly mer copolymerizable acetophenone or benzophenone derivatives contains. 9. Use of polymers, which 0.2 to 80 wt .-%, bezo gene on the polymer, from oligopropene derivatives of the formulas I, II or III exist as adhesives. 10. Use of polymers according to claim 9 as a hot melt adhesive fabrics. 11. Use of polymers according to claim 9 as by energy rich radiation crosslinkable adhesives. 12. Use of polymers according to one of claims 9 to 11 as pressure sensitive adhesives. 13. coated with adhesives according to one of claims 1 to 8 substrates.