IL35933A - A method for the production of a plastics dispersion for use as additive to mortar - Google Patents

Description

A method for the production of a plastics dispersion for use as additive to mortar n»o naoina t aof «ηοα'ο ain n» an -m"^ τ*?ηη This Invention relates to a method for the preparation of a finely divided, aqueous , al kal i -resistant plastics dispersion consisting of using an admixture of a vinyl chloride copolymer with polymerizable Internal ly plastidzed monomers , wi th a glass transition point tem- a perature for the formed film of said copolymer of about 15 - 25 C, to improve the adhesion force of the setting mortar.

It is well known that aqueous dispersions of polymers are added to concrete, in order to Improve its properties such as tensi le strength , bending strength , resistance to abrasion and cracking. The addition of such dispersions should not prove deleterious by retarding the hardening process or i ncreasing the water retaini ng power and so on. Satisfactory resul ts were obtained especial ly wi th alkal i -resistant dispersions consisting of copolymers of styrenebutadiene , acryl ic and methacryllc esters and vinyl chloride wi th vinyl and acryl ic esters as wel l as with terpolymers of vinyl chloride , vinyl ester and ethylene (according to the process discl osed in Dutch Patent 6807369 ) , with a range of vinyl chloride from 5 percent by weight.

One of the most difficul t problems in masonry 1s the ^effectiveness of the adhesi ve material used as the binding layer between separate bricks since poor adhesion causes damage to the bricks during the continuous process of setting which a bricked structure undergoes .

Among the available plastic dispersions us^ed as mortar setting admixtures for masonry, satisfactory resul ts have been obtained only with dispersions of copolymers consisting of vinyl 1dene chloride and methaer ^e esters copolymers of acryl ic and methacryl lc esters .

The drawback when using dispersions of vinyl 1dene chloride consists In the partial decomposi tion of the vlnyl ldene polymer and the formation wi th the components of the mortar of considerable amounts of calcium chloride , which induces corrosion and destruction of the iron or stee l reinforcing rods .

Dispersions of acryl ic and methacryl lc esters on the other hand are expensive to be used as a rule 1n admixture wi th mortar.

It 1s the object of this invention to provide a plastics dispersion used as an admixture to mortar in order to Improve Its adhesive strength.

According to the method of this Invention 1t has been found that usi ng the dispersi on obtained this purpose is achieved /by polymerization of a mixture of monomers consisting of from 30 to 80 weight percent vinyl chloride and 20 to 70 wiight percent polymerizable internal ly plasticized monomers in aqueous solution, which based on the total content of the monomers consists of a) 3 to 6 percent by weight of an emulsifler mixture consisting of 60 to 90 percent by weight of emulsifiers of the non-1on1c type and 10 to 40 percent by weight of emulsifiers of the anionic type, b) a polymerization catalyst c) 2 to 4 percent by weight of an aqueous solvent for the obtained polymer, d) 0.3 to 0.5 percent by weight water-soluble monomer added for copolymer! zati on, e) buffer. and the subsequent addition to the obtained plastics dispersion of 0.5 to 5 percent by weight based on the total weight of the dispersion , of an emulsifler of the anionic type and 0.1 to 0.5 percent by weight, based on the total weight of the dispersion , of an antifoam agent.

The most suitable Internal ly plasticized monomers are esters of acrylic acid such as butyl acrylate, ethylhexyl acrylate, esters of maleic and itaconic acid, vinyl esters as vi nyl acetate , vi nyl propionate , vinyl laurate , vinyl ethyl butyrate and vinyl ethyl hexanoate. Ethylene can also be used as a suitable Internal ly pl asticized monomer.

Obviously, also combinations of the monomers may be used.

The amount of vinyl chloride to be used 1s 1n the range of 30 to 80 perce(¾/ by weight is dependent on the other monomers used. The composition formed from has to be chosen such that the films-of said copolymer obtained have glass transition point temperature ranging from T5 to 25°C, preferably from 15 to 20°C. When using for example ethylene as a second component, the amount of vinyl chloride can range up to 80 percent. If acrylic esters are used, up to 60 percent by weight of vinyl chloride is used. The use of less than 30 percent vinyl chloride should be avoided, in order to preserve the alkali -resistance of the dispersion.

The emulslfler mixture, which consists of 20 to 40 percent of the anionic type and 60 to 80 percent of the non-ionic type, is of importance. The anionic to non-1on1c emulsifier ratio appears to affect considerably the adhesiveness and the amount of water to be admixed with the mortar. Polymerization in the absence of anionic emulsifiers results 1n a considerably increased water to cement ratio. If the polymerization is carried out injthe absence of non-ionic emulsifier, the mortar exhibits poor adhesiveness. The subsequent modification of the dispersion by addition of the anionic emulsifier to the polymerized dispersion is also of decisive Importance.

As non-1on1c emulsifiers ethyl eneoxy-propyleneoxy polymers , ethyleneoxyalkyl phenol polymers , ethyleneoxyalcohol polymers , for example ethyl eneoxynonyl phenol condensates , ethyl eneoxylauryl alcohol condensates are chiefly used.

The anionic emulsifiers mainly used are alkyl , aryl , or alkaryl sulfonates , sulfuric esters of alcohols with 8 to 18 C-atoms, polyethylene-oxy alkyl phenyl sulfonates , polyethyleneoxy alcohol sulfates.

The water-soluble solventss mainly used for the polymerization product are polyol compounds as glycol butyl ether, butyl ester of glycol 1c add, hexyleneglycol and the like.

The water soluble monomers for copolymerization are acrylic add, methacrylic add, sodium methallyl sulfonate.

As antifoam agents nonylalcohol , si licone compounds , and polyethyleneoxy compounds give good results.

TJie dispersions prepared according to the process of the invention are alkali resistant and exhibit good adhesive properties. The average diameter of the particles of synthetic resin is less than o.3 y. to 50 percent by weight of the dispersion, based on the weight of gypsum the hydraulic binding materials of the mortar (llme.-gtpsum, cement mortar) , s added to the mortar mixes In order to improve the adhesiveness of the set mortar. Due to the considerable improvement 1n adhesiveness , prefabricated wall units may be processed from building bricks using this mortar admi xture setting^ without running the risk of the building bricks fal ling apart during transport.

In addition to this principal application, the dispersion propose^ in this Invention can be also used as adhesive agent for dispersion dyes and pigments.

The following examples la, 2a, 3a and 4a, which serve to Il lustrate the process of this Invention, are compared to the examples 1 , 2, 3 and ,4 in order to show the Importance of the subsequent addition of the anionic emulsiflers, for the same emulslfier and monomer composition, as well as to the examples 5 to 8, where emulsiflers and monomers of different composition are used (see table p. 10a) .

EXAMPLE 1 In a 2 litre jacketed stainless-steel autoclave equipped with a stirrer and a feed tank for the monomers , the following aqueous phase was placed: 570 g delonized water g hexylene glycol (water-soluble solvent) 3 g acrylic add (water-soluble monomer) 18 g non-1on1c emulslfier (consisting of propylene oxlde/ethylene oxide with 80 percent ethyl eneoxide) 3 g anionic emulslfier (sodiumlauryl sulfate) 3 g sec. sodium phosphate (buffer) 3 g potassium persulfate (catalyst) Example la After sealing and flushing the autoclave with nitrogen, a monomer mixture, consisting of 270 g vinyl chloride (VC) 210 g vinyl propionate (VP) and 120 g bjtyl' acrylate (BA) i ncl uding also 12 g of a non 1on1c emulslfler consisting of propylene oxide/ethyl ene oxide wi th 50 percent ethylene oxide as non-Ionic emulslfler, was gradually added within 3 to 4 hours and heated to 68 to 70°C to effect polymerization. After 2 more hours the autoclave was flushed with ai r and the pH adjusted to 55 with sodium carbonate.

The resul ting dispersion has the fol lowing characteristics : sol Ids content 53 % particle size <0.3μ PVC content 43 ¾ glass transition point temperature 17°C. 0.5 weight percent of an si licon antlfoam agent based on the weight of the total dispersion was added. The dispersion resul ting from Example 1 was used as such , without addition of an anionic emulslfler. The dispersion resulting on the addition of 3 weight percent of an anionic emulslfler (Manox produced by Hercules Co. ) , based on the total weight of the dispersion, for the preparation of a mortar havi ng the fol lowi ng composition: Quartz sand, granul ef|of from 0 to 1 mm 648 g " " 1 to 4 mm 648 g Portland cement 545 g dispersion according to example 1 135 g plastics to cement ratio 0,125 The tensile strength was determined by bonding with the above mentioned mortar, of two bricks with an average specific absorption capacity of 30 to 40 g/ cm$n1 n and total bonding surface of 144 cm set with the above described mortar. The thickness of the mortar was of 6 mm. After 8 days storage at °C and 65% relative atmospheric humidity the tensile strength was determi ned. The obtained values are set forth 1n the table below.

Example 2 In the autoclave used in example 1 and la was placed an aqueous solution of the fol lowing composition: 570 g delonized water g glycol monobutyl ester (sol vent) 3 g acryl ic acid (water-soluble monomer) 4.5 g anionic emulslfier (sodium salt of diethylsulphosucdnate) 12 g non-1on1c emulslfier (consisting of ethylene oxlde/propylene oxide 3 g sodium bicarbonate 3 g sc. sodium phosphate 3 g potassium persulfate Example 2a In an aqueous solution, a mixture consisting of 300 g vinyl chloride (VC) , 300 g vinyl propionate (VP) and 9 g of a non ionic emulslfier consisting of ethylene oxide and propylene oxide as non-ion1c emulsl fier was polymerized at a constant pressure of 20 atm. The resul ting dispersion has the following characteristics : sol ids content 54 to 55 % particle size <0.3 μ VC - content 41 % a formed from the dispersion Glass transition point temperature of the #«¾Ί9 C.

The resul ti ng dispersion was worked up and tensi le strength was determined according to the procedure given in Example la.

Example 3 As 1n example 1 and la a dispersion was polymerized , the composi tion of the aqeuous solution bei ng: 570 g delonized water g of polyglycol derivatives (solvent) 3 g acryl ic add g non-1on1c emulsifier (consisti ng of ethylene oxide/ 3 g anionic emulsi fier (sodiumlauryl sul fate) 3 g sodium bicarbonate 2 g sec. sodium phosphate 3 g potassium persulfate Example 3a The mixture of monomers consisting of 210 g vinyl chloride (VC) , 150 g vinyl acetate (VA) and 240 g butylacrylate (BA) , Incl uded also 6 g of an ethylene oxide and propylene oxide as non Ionic emulsifier.

The resul ting dispersion had the fol lowing characteristics : sol Ids content 53 ¾ particle size <0.3u PVC content 33 % a fi lm formed from the dispersion glass transition point temperature of the-f††m 15 C.

The resulting dispersion was worked up and tensi le strength was determined according to the procedure given in Example la.

Examples 4 and 4a As in examples 3 and 3a a dispersion was prepared , using i nstead of butyl aery late in the monomer mixture the same amount of d1 butyl maleate (DB ) .

The resul ting dispersion has the fol lowing characteristics : sol ids content 52 ¾ particle size <0.3u PVC content 31 % a fi lm formed from the di spersion glass transition point temperature of the_f11m 20 C.

The dispersion was worked up and tensi le strength was determined according to the procedure given in Example la.

Example 5 A dispersion was prepared as i n examples 3, except that the emulsifier in the aqueous phase consisted of 12 g of the ammonium sal t of a sulfate ester of an al kyl -phenoxy-polyethylene alcohol (anionic emulsi fier) and 9 g of an ethylene oxide/propylene oxide (non-Ionic emulslfier) . To the mixture of monomers 6 g non-1on1c emulslfier were also added.

The resulting dispersion had the fol lowing characteristics : sol Ids contBnt 52 % particle size < 0.3 u PVC content 31 nX a fi lm formed from the -dispersion glass transition point temperature of -th -- 4 fn- 16 C As shown in the table, the mortar obtained with this dispersion 2 has a tensi le strength of only 0.5 kg/C^. A subsequent addition of anionic emulslfier did not considerably improve the tensi le strength of the mortar. Example 6 A dispersion was prepared as 1n example 3, but without the addition of a polyglycol to the aqueous solution. The resulting dispersion had the fol lowing characteristics : sol id content 52 % particl e size 0.4 to 0.8 μ PVC content 31 % a fi lm formed from the dispersi on glass transition point temperature of the-f hn 19 C The tensile 'Strength;, of the binding layer obtained with the 2 mortar usi ng this dispersion is 1 kg/em .

The addition of anionic emulslfier to the dispersion did not greatly Improve the above resul t.

Example 7 A dispersion was prepared as in example 3, but the monomer composition was selected so as to obtain a glass transition point temperature of 29°C, outside thet of the range of the Invention. The sol ids content was 52.5 percent, the particle size under 0.3 μ and the PVC content 42.5 percent. The obtai ned tensile strength of the mortar produced using 2 this dispersion was very low (1 .0 kg/cm ) .

Example 8 In order to prove the importance of the addition of anionic emulslfie s to the dispersion obtained, In example 2, 3 percent of a non-1on1c emulslfler was added. The tensi le strength of the 2 mortar produced was 1 kg/cm , as can be seen 1n the table below.

The table gives the composition of the emulslflers , I .e. also the emulslflers reacting with the monomers as represented in the column "emulslfler composition" . o.5 Bercent antifoam agent was added to every dispersion.

T A B L E Example composition of composition of emulslfier monomers non-ionic anionic L 90% 10% vinyl chloride 270 9 vinyl propionate 210 g butyl acrylate 120 g la 90% 10% as in 1 2 82.5% 17.5% vinyl chloride 300 g vinyl propionate 300 g ethylene at a pressure of 20 atm. 2a 82.5% 17.5% as 1n 2 3 87.5% Ίέ.5% vinyl chloride 2l0 g vinyl acetate 150 g butyl acrylate 240 s 3a 87.5% 12.535 as in 3 4 87.5% 12.5% vinyl chloride 210 g vinyl acetate 150 g d1 butyl maleate 240 g 4a 87.5% 12.5* as In 4 55. H 44.5% as in 3 6 87.5% 12.5% as in 3, but without solvent in the aqueous phase 7 87.5% 12.5% vinyl chloride 270 g vinyl acetate 210 g butyl acrylate 120 glass transition pt. vitrification- temp. 29 Ί 8 90% 10% as in 1

Claims (5)

35933/3 What we claim 1s :

1. A method for the preparation of an aqueous , finely dispersed , al kal i -resistant, plastics dispersion used as an additive to Improve the adhesiveness of setting mortar consisting of a copolymer of vhyl chloride with polymerizable, internal ly piastlclzed monomers havi ng glass transition point temperature of of said copolymer of 15 - 25°C , comprising polymerizing a mixture of monomers , consisting of from 30 to 80 weight percent vin l chloride and 20 to 70 weight percent polymerizable Internally piastlclzed monomers in the presence of an aqueous phase which , based on the total content of the monomers , consists of: a) 3 to 6 weight percent of an emulsifier mixture consisting of 60 to 90 weight percent of emuls1f1ers of the non-1 onlc type and 10 to 40 weight percent of emulsifiers of the anionic type , b) a polymerization catalyst, c) 2 to 4 weight percent of a water soluble solvent for the obtained polymer, d) 0.3 to 0.5 weight percent water-soluble monomer added for copo- lymerlzation, e) buffer and subsequently adding to the ebtained dispersion 0.5 to 5 weight percent, based on the total weight of the dispersion, of an emulsifier of the anionic type and 0.1 to 0.5 weight percent, based on the total weight of the dispersion, of an antlfoam agent.

2. The method of claim 1 wherein the internal ly piastlclzed monomers used are esters of acrylic add and/or vinyl esters and/or ethylene .

3. The method of claim 1 wherein the Internally pl asticized monomers used are maleic acid and/or itaconlc add esters .

4. The method of claim 1 to 3 wherein the copolymerizable water-sSl uble monomers used are acryl ic and/or methacrylic acid.

5. The method as hereinbefore described with reference to the examples 1-7. For the Appl icant Wol ff, Bregman and Gol ler