DE3920935A1 - Aq. dispersion useful as contact adhesive - contg. e.g. acrylic] copolymer and vinylidene] chloride copolymer - Google Patents

Abstract

An aq. dispersion is claimed which consists of (i) at least one resin (A) of Tg -55 to -10 deg.C and wt. ave. mol. wt. 200,000-1 million; and (ii) at least one resin (B) of Tg 0-30 deg.C, the wt. ratio (A):(B) being 95:5-10:90. Resin (A) consists of (a) 65-97 wt.% of vinyl acetate, vinyl propionate and/or acrylic ester of a 2-10C alkanol; (b) 0-30 wt.% acrylonitrile, styrene and/or methacrylic ester of a 1-5C alkanol; and (c) 0-5 wt.% of one or more 3-5C alpha, beta-mono ethylenically unsatd. mono- or di-basic acids or anhydrides, mono- or di-amides, alkali metal salts or (in the case of dibasic acids) 1-8C alkanol semi-esters of the acids. Resin (B) consists of (a) 75-93 wt.% vinylidene chloride; (b) 7-25 wt.% acrylonitrile and/or (meth)acrylic esters of 1-8C alkanols, opt. with up to 10 wt.% of such monomers being replaced by hydroxyethyl- or hydroxypropyl-acrylate; and (c) 0-5 wt.% of one or more of 3-5C alpha, beta-monoethylenically unsatd mono- or di-carboxylic acids or their mono- or diamides as well as 2-acrylamido-2-Me-propanesulphonic acid (2-AM Claimed prepn. of the aq. dispersion is by bringing together at least one dispersion contg. (A) with at least one dispersion contg. (B). USE/ADVANTAGE - Use of the aq. dispersion is claimed as a contact adhesive. Such adhesives have higher strength than those of EP-185465.

Description

The present invention relates to aqueous synthetic resin dispersions, containing

• A) at least one synthetic resin A consisting of
  • a) 65 to 97% by weight of at least one monomer from the series vinyl acetate, vinyl propionate and ester of acrylic acid with alkanols containing 2 to 10 carbon atoms (monomers I),
  • b) 0 to 30 wt .-% of one or more monomers from the series acrylonitrile, styrene and esters of methacrylic acid with alkanols containing 1 to 5 carbon atoms (monomers II) and
  • c) 0 to 5 wt .-% of one or more monomers of 3 to 5 carbon atoms containing α, β-monoethylenically unsaturated mono- and / or dibasic acids, anhydrides of these acids, mono- and / or diamides of these acids, alkali metal salts of these Acids and half-esters of dibasic acids with alkanols containing 1 to 8 carbon atoms (monomers III), in copolymerized form, and
• B) at least one synthetic resin B consisting of
  • a) 75 to 93% by weight of vinylidene chloride (monomer IV),
  • b) 7 to 25% by weight of at least one monomer from the series acrylonitrile, esters of acrylic acid with alkanols containing 1 to 8 C atoms and esters of methacrylic acid with alkanols containing 1 to 8 C atoms, with up to 10% by weight % of these monomers can be replaced by hydroxyethyl acrylate and / or a hydroxypropyl acrylate (monomers V) and
  • c) 0 to 5% by weight of one or more monomers composed of α, β-monoethylenically unsaturated mono- and / or dicarboxylic acids, mono- and / or diamides of these carboxylic acids and the 2-acrylamido-2- methyl propanesulfonic acid (monomers VI), in copolymerized form,

with the proviso that the mass ratio of the at least one synthetic resin A to the at least one resin B 95: 5 to 10: 90, the glass transition temperature from A -55 to -10 ° C, the glass transition temperature of B 0 to 30 ° C and the weight average molecular weight of A 2 · 10⁵ to 10⁶ is.

The invention also relates to the method for producing this aqueous resin dispersions and the use of these aqueous Resin dispersions as contact adhesives.

EP-B 1 85 465 relates to aqueous synthetic resin dispersions containing at least one amorphous synthetic resin, the molecular weight distribution of which is the maximum has a molecular weight Mp of 100,000 to 700,000 and the Glass transition temperature is -50 to <0 ° C, and at least one crystalline, vinylidene chloride copolymerized, containing synthetic resin, whose glass transition temperature is not greater than 80 ° C, included with with the proviso that the mass ratio of the at least one amorphous Resin to the at least one crystalline resin 95: 5 to Is 10:90. Preferred, and disclosed only by way of example, are aqueous resin dispersions, the amorphous resin 10 to 70% by weight vinylidene chloride, 30 to 90% by weight at least one plasticizing comonomers, 0 to 50% by weight of vinyl chloride and 0 to 10% by weight of at least one copolymerizable ethylenically unsaturated Polymerized acid contained. These aqueous synthetic resin dispersions are particularly recommended as contact adhesives. A disadvantage of this aqueous resin dispersions disclosed by way of example, however, is that when used as contact adhesives, the strength of the resulting bondings can not fully satisfy.

The present invention was therefore based on the provision of aqueous Synthetic resin dispersions used in contact adhesives Adhesions with increased strength result as a task. Accordingly, the aqueous resin dispersions defined at the outset found.

As monomers I are in particular the esters of acrylic acid with n- and Isobutanol and with 2-ethylhexanol of interest. Preferred monomers II are methyl methacrylate and acrylonitrile. Advantageously, A1 contains 4 to Polymerized 20 wt .-% of monomers II. Coming as monomers III in particular containing α, β-monoethylenically unsaturated 3 to 5 carbon atoms Mono- and dicarboxylic acids and their amides into consideration. As another Monomer III is the sodium salt of vinyl sulfonic acid of interest. Monomers III polymerized into the synthetic resins A are particularly preferred  are the acrylic and methacrylic acid as well as the amides of these α, β-monoethylenically unsaturated carboxylic acids. In a particularly advantageous way A contains mixtures of these monoethylenically unsaturated Polymerized carboxylic acids and their amides. Overall, the Weight shares of the monomers involved in the synthesis of synthetic resins A. Using the relationship of Fox chosen so that A is a glass transition temperature from -55 to -10 ° C. After Fox (T. G. Fox, Bull. Am. Phys. Soc. (Ser. II) 1, 123 (1956)) applies to the glass transition temperature of Mixed polymerisation in good approximation:

where x¹, x²,. . ., x ⁿ the mass fractions of the monomers 1, 2,. . ., n and Tg¹, Tg²,. . ., Tg ^{n are} the glass transition temperatures of only one of the monomers 1, 2,. . . or n built polymers in degrees Kelvin. The glass transition temperatures of these homopolymers of the monomers listed above are known and z. B. in J. Brandrup, EH Immergut, Polymer Handbook 1 ^st Ed. J. Wiley, New York 1966, 2 ^nd Ed. J. Wiley, New York listed in 1975.

The applied the synthetic resins A according to the invention in aqueous dispersion , they are preferably by polymerization of the respective Monomers in an aqueous medium under the known conditions of Emulsion polymerization in the presence of water-soluble radical-forming Initiators and emulsifiers and optionally in the presence of Protective colloids and regulators as well as other aids.

Nonionic and anionic in particular have been found as emulsifiers Proven surfactants. Preferred nonionic surfactants are ethoxylated alkanols (EO grade: 6 to 50, alkyl radical: C₈ to C₁₈), ethoxylated alkylphenols (EO grade: 6 to 50, alkyl radical: C₈ to C₁₂) and ethoxylated aliphatic monocarboxylic acids (EO grade: 6 to 50, alkyl radical: C₁₂ to C₁₈). The preferred anionic surfactants are Alkali metal salts of sulfated derivatives containing 6 to 18 carbon atoms Alkanols, ethoxylated alkanols (EO grade: 4 to 30, alkyl radical: C₁₂ to C₁₈) and of ethoxylated alkylphenols (EO grade: 4 to  30, alkyl radical: C₆ to C₁₂) and the alkali metal salts from 12 to Alkanesulfonic acids containing 18 carbon atoms.

Peroxides are the main water-soluble polymerization initiators such as the alkali metal peroxydisulfates, hydrogen peroxide or combined Systems containing an organic reducing agent, a peroxide and a small amount of a metal compound soluble in the polymerization medium, whose metallic component can occur in several valence levels, included, e.g. B. ascorbic acid / iron (II) sulfate / sodium peroxydisulfate, in Consider, with the sodium salt often in place of ascorbic acid of hydroxymethanesulfinic acid, sodium sulfite, sodium hydrogen sulfite or Sodium metabisulfite is used.

The emulsion polymerization temperature and the amount of polymerization initiators used is measured in a manner known per se so that a weight-average molecular weight _{w of} the dispersed synthetic resin A of 2 × 10⁵ to 10⁶ is obtained. As a rule, the emulsion polymerization temperature is 30 to 90, preferably 50 to 85 ° C., and the polymerization initiators are usually used in amounts, based on the monomers, of 0.1 to 1.5% by weight. Resins A having high _w values are preferred.

The amount of emulsifier used essentially determines the average Diameter of the resulting dispersed resin particles. It is preferably chosen so that small synthetic resin particles are formed. A measure of the average diameter of the dispersed synthetic resin particles is the light transmittance (LD value) of the aqueous synthetic resin dispersion. The synthetic resins A are preferably prepared in an aqueous emulsion in such a way that the resulting initial dispersions when diluted to one Solids content of 0.01 wt .-% an LD value, measured with a commercial photometer (at a wavelength of 0.546 µm) at a Layer thickness of 25 mm relative to water (which arbitrarily has an LD value of 100 is assigned), an LD value of 40 to 90, particularly preferably of Have 55 to 85. In order to obtain such initial dispersions, usually, based on the amount of monomers, 0.5 to 5 wt .-% Emulsifiers are used.

The emulsion polymerization for the production of the synthetic resin A can both carried out as a batch process and in the form of a feed process will. The feed process is preferred, in which one part of the Submits polymerization approach, heated to the polymerization temperature and then the rest in separate feeds, one of which is the Contains monomers in pure or in emulsified form,  feeds continuously. The monomers are fed as an aqueous emulsion prefers. The solids content of those obtainable, A in dispersed Form-containing aqueous starting dispersions is preferably 30 to 60, particularly preferably 45 to 55% by weight.

The synthetic resins B preferably contain methacrylate as monomers V, Ethyl acrylate, n-butyl acrylate, methyl methacrylate, hydroxyethyl acrylate and Polymerized acrylonitrile. As monomers VI are in particular Acrylic acid, methacrylic acid and the amides of these two acids from Meaning, mixtures of these monomers particularly preferred in B be polymerized.

Groups of synthetic resins B with particularly good suitability consist of Units of monomers of the following composition in polymerized Shape:

• i) 87 to 93 wt .-% vinylidene chloride and
  8 to 13% by weight of at least one monomer from the series acrylonitrile, methacrylate, methyl methacrylate and ethyl acrylate,
• ii) 85 to 90% by weight vinylidene chloride and
  10 to 15% by weight of at least one monomer from the series n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate and tert-butyl acrylate,
• iii) 75 to 85% by weight vinylidene chloride and
  15 to 25% by weight of 2-ethylhexyl acrylate and / or n-hexyl acrylate.

Furthermore, synthetic resins B are of interest, which have a composition have obtained by mixing the composition i) to iii) can be. In general, the proportions by weight of the structure of the Synthetic resins B monomers chosen so that the glass transition temperature from B is 0 to 30 ° C. Fox 's relationship or comparable relationships between the monomer composition of a Copolymer and the glass transition temperature Tg of this copolymer cannot be copolymers containing vinylidene chloride apply. However, a sufficient assessment of this relationship is in many cases on the basis of in "Polyvinylidene Chloride", R. A. Wessling, Gordon and Breach, Science Publishers 1977 possible, the dependence of the glass transition temperature on the Composition of copolymers containing vinylidene chloride point out. In addition, the glass transition temperature can be known can be determined by preliminary tests.  

The synthetic resins B, like the synthetic resins A, are preferably in aqueous Medium under the known conditions of emulsion polymerization in Presence of water-soluble free radical initiators and emulsifiers as well as optionally other aids. Preferably are the same radical initiators and emulsifiers as in the Emulsion polymerization used for the production of synthetic resins A. The Emulsion polymerization temperature is advantageously 30 to 70, particularly preferably 40 to 60 ° C. Due to the low boiling point of the Vinylidene chloride is advantageously polymerized in pressure vessels. The feed process is preferably used. The Molecular weight of resins B is compared to the molecular weight of synthetic resins A of minor importance. If you work with the same Amounts of initiator as in the emulsion polymerization for the preparation of A are usually emulsion polymers B with a weight average Molecular weight of 5 · 10⁴ to 5 · 10⁵ obtained. Advantageously are used to produce B combined initiator systems, the one organic reducing agent, a peroxide and a small amount of an im Contain polymerization medium soluble transition metal compound, used. The emulsion polymerization for the production of B Amounts of emulsifier used are based on the amount used of monomers, preferably 1.5 to 3.5% by weight. This usually leads to B as the disperse phase containing aqueous starting dispersions LD value is 70 to 90. The solids content of these B-containing Starting dispersions are preferably 30 to 65, particularly preferably 45 up to 55% by weight.

The inventive, at least one resin A and at least one Aqueous synthetic resin dispersions containing synthetic resin B are in application technology advantageously available by at least one an initial dispersion containing synthetic resin A and at least one Resin B containing starting dispersion together, z. B. by which mixes one initial dispersion into the other. The quantities will be dimensioned so that the mass ratio of the at least one synthetic resin A to the at least one synthetic resin B in the resulting invention aqueous resin dispersion 95: 5 to 10: 90, preferred 50: 50 to 80: 20. The total solids content of synthetic resins A and B in the aqueous resin dispersions according to the invention preferably 30 to 65% by weight.

The aqueous synthetic resin dispersions according to the invention are suitable especially as contact adhesives. The advantage here is the increased Strength of the resulting bonds. Suitable as contact binders the aqueous synthetic resin dispersions according to the invention in particular for Bonding of plastics, metals, leather, felt, textile fabrics, wood,  Cork and paper. Adapted to the respective substrate aqueous resin dispersions according to the invention additionally contain tackifying resins and / or inert fillers.

example Roller peeling tests, based on DIN 53 289, to examine the Strength of bonds, made using the one hand synthetic resin dispersions D1 to D5 according to the invention and on the other hand prepared using the comparative dispersions V1 to V3 a) Starting dispersions

As starting dispersions containing at least one synthetic resin A, were the 50 wt .-% aqueous resin dispersions A1 and A2 used.

A1: Containing, as synthetic resin A, a copolymer which consists of

94.4% by weight of n-butyl acrylate
3% by weight acrylic acid
2% by weight methyl methacrylate
0.4 wt .-% sodium vinyl sulfonate and
0.2% by weight methacrylamide,

in polymerized form.

Tg: -36 ° C; LD value: 58
_w : 160,000; Mp: 120,000

The weight average molecular weight _w and the molecular weight Mp at the maximum of the molecular weight distribution were determined in all cases by the method of high pressure gel permeation chromatography, with calibration using linear polystyrene. Tg was determined by differential scanning calorimetry.

A2: Containing, as synthetic resin A, a copolymer which consists of

76.5% by weight of n-butyl acrylate
19.9% by weight methyl methacrylate
3% by weight acrylic acid
0.4 wt .-% sodium vinyl sulfonate and
0.2% by weight of acrylamide,

in polymerized form.

Tg: -19 ° C; LD value: 55
_w : 126,000; Mp: 120,000

As starting dispersions containing a comparison resin AV, the 50 wt .-% aqueous resin dispersions AV1 and AV2 used.

AV1: Containing as a comparative resin a copolymer that consists of

70% by weight 2-ethylhexyl acrylate
28% by weight vinylidene chloride and
2% by weight acrylic acid,

in polymerized form.

Tg: -35 ° C; Mp: 108,000

AV2: Containing as a comparative resin a copolymer that consists of

69.3% by weight of n-butyl acrylate
28.7% by weight of vinylidene chloride and
2% by weight acrylic acid,

in polymerized form.

Tg: -13 ° C; Mp: 135,000

As starting dispersions containing at least one synthetic resin B, the 50 wt .-% aqueous resin dispersions B1 to B3 used.

B1: Containing, as synthetic resin B, a copolymer which consists of

84.2% by weight vinylidene chloride
9.3% by weight methacrylate
2.8% by weight acrylic acid
2.8% by weight of hydroxyethyl acrylate and
0.5% by weight of 2-acrylamido-2-methyl-propanesulfonic acid,

in polymerized form.

Tg: 14 ° C; LD value: 73
_w : 130,000

B2: Containing a copolymer as synthetic resin B, which consists of

90.8% by weight vinylidene chloride
8.2% by weight of methacrylate and
1% by weight acrylic acid,

in polymerized form.

Tg: 16 ° C; LD value: 89
_w : 90,000

B3: Containing as a synthetic resin B a copolymer that consists of

90.5% by weight vinylidene chloride
5% by weight acrylonitrile
4% by weight of methacrylate and
0.5% by weight acrylic acid,

in polymerized form.

Tg: 16 ° C; LD value: 91
_w : 110,000

The starting dispersions were weight ratio as follows 75: 25 to the dispersions D1 to D5 and V1 to V3 combined:

b) roll peeling tests 1. Cotton fabric as a substrate Production of the bond

The freshly produced 50% by weight synthetic resin dispersions D1 and D3 to D5 as well as V1 to V3 were respectively on a half strip length on a cotton strip (Length 22 cm, basis weight 465 g / cm²) applied (Dry weight of the order quantity = 30 g / m²). after the applied mass was dry (15 to 20 min), was applied the same half of the cotton strip, in the same amount second order applied. After drying this second Application mass (20 to 30 min) was the coated Surfaces of two identical synthetic resin dispersions Cotton strips by rolling over with a hard rubber roller, applying pressure through the hard rubber roller operating person, pressed together.

Peel test

Both immediately after making the bond as well after the composite has been stored for 7 days under normal conditions, in analogy to DIN 53 289, the no adhesive having halves of the glued together Angled stripes and on one of her non-glued thighs about a roll by a traction, at a Pulling speed of the pulling clamp of 100 mm / min, loaded until the adhesive layer tore and both Sample halves were separated. The each required pulling force (separating force) was dependent on the adhesive layer length registered in a peeling diagram. Subsequently, the middle of the peeling diagram (i.e. between 15 and 85% of the chart length) arithmetic averaging determines the average separation force and from this the average peel resistance (force in N per width of the sample in mm). The results obtained show the Table 1. The values given represent mean values of 4 examinations each.  

Table 1

2. Synthetic leather based on vulcanized styrene-butadiene rubber as a substrate Production of the bond

The freshly produced 50% by weight synthetic resin dispersions D2, D5 and V1, V3 were each assigned to one Faux leather stripes (length 22 cm, width 25 cm, weight per unit area 4.2 kg / m²) applied (dry weight of the application quantity = 40 g / m²). After the applied mass was dry (45 to 75 min) the coated areas of two identical synthetic resin dispersions showing synthetic leather stripe 15 sec using a Stamp pressure of 200 bar pressed together.

Peel test

Like when gluing the cotton fabric. The results shows Table 2.

Table 2

Claims (6)

1. Aqueous synthetic resin dispersions containing

• A) at least one synthetic resin A consisting of
  • a) 65 to 97% by weight of at least one monomer from the series vinyl acetate, vinyl propionate and ester of acrylic acid with alkanols containing 2 to 10 carbon atoms (monomers I),
  • b) 0 to 30 wt .-% of one or more monomers from the series acrylonitrile, styrene and esters of methacrylic acid with alkanols containing 1 to 5 carbon atoms (monomers II) and
  • c) 0 to 5 wt .-% of one or more monomers of 3 to 5 carbon atoms containing α, β-monoethylenically unsaturated mono- and / or dibasic acids, anhydrides of these acids, mono- and / or diamides of these acids, alkali metal salts of these Acids and half-esters of dibasic acids with alkanols (monomers III) containing 1 to 8 carbon atoms, in copolymerized form, and
• B) at least one synthetic resin B consisting of
  • a) 75 to 93% by weight of vinylidene chloride (monomer IV),
  • b) 7 to 25% by weight of at least one monomer from the series acrylonitrile, esters of acrylic acid with alkanols containing 1 to 8 C atoms and esters of methacrylic acid with alkanols containing 1 to 8 C atoms, with up to 10% by weight % of these monomers can be replaced by hydroxyethyl acrylate and / or a hydroxypropyl acrylate (monomers V) and
  • c) 0 to 5% by weight of one or more monomers composed of α, β-monoethylenically unsaturated mono- and / or dicarboxylic acids, mono- and / or diamides of these carboxylic acids and the 2-acrylamido-2- methyl propanesulfonic acid (monomers VI), in copolymerized form,

with the proviso that the mass ratio of the at least one synthetic resin A to the at least one resin B 95: 5 to 10: 90, the glass transition temperature from A -55 to -10 ° C, the glass transition temperature of B 0 to 30 ° C and the weight average molecular weight of A 2 · 10⁵ to 10⁶ is. 2. Aqueous synthetic resin dispersions according to claim 1, which contain at least one synthetic resin B consisting of units of monomers of the compositions i to iii)

• i) 87 to 93 wt .-% vinylidene chloride and
  8 to 13% by weight of at least one monomer from the series acrylonitrile, methacrylate, methyl methacrylate and ethyl acrylate,
• ii) 85 to 90% by weight vinylidene chloride and
  10 to 15% by weight of at least one monomer from the series n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate and tert-butyl acrylate,
• iii) 75 to 85% by weight vinylidene chloride and
  15 to 25% by weight of 2-ethylhexyl acrylate and / or n-hexyl acrylate

exists in polymerized form, or that is a monomer composition which by mixing compositions i) to iii) can be obtained. 3. Process for the preparation of aqueous synthetic resin dispersions according to claims 1 or 2, characterized in that one aqueous dispersion containing at least one resin A and an aqueous containing at least one synthetic resin B. Output dispersion together. 4. Use of aqueous synthetic resin dispersions according to claims 1 or 2 as contact adhesives.