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DisperDispercoll C Pcoll C Polyolychlorchloroproprene Laticesene Laticesfor Adhesivfor Adhesive Applications:e Applications:

PPrroperoper ties and Compounding Guide ties and Compounding Guide

DispercollDispercoll ®® CC

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Dispercoll® C Polychloroprene Latices forAdhesive Applications: Properties andCompounding GuideIntroductionBayer has long history with polychloroprene rubber for adhesive applications. Polychloroprene latices have been soldunder the Dispercoll C trade name for adhesive applications for over 25 years. Dispercoll C latices provide a safe and envi-ronmental friendly alternative to solvent based adhesives. Dispercoll C latices have been found to be an excellent alterna-tive to solvent based adhesives that used non-flammable solvents. Dispercoll C latices can be used to formulate adhesiveswhich meet many of the VOC regulations and also greatly reduce fire hazards that have been associated with flammablesolvents. The advantages of using water borne systems have pushed their growth rate above solvent based polychloro-prene adhesives.

ApplicationsBayer Material Science offers three different grades of Dispercoll C polychloroprene latices. Dispercoll C-84 is a strongcrystallizing grade which has high tensile strength. Dispercoll C-74 is a medium crystallizing grade with high heat resist-ance. Dispercoll C LS 2372H is a low crystallizing grade with high degree of tackiness and long contact bond life. Eachproduct's unique properties lend themselves to different applications. Dispercoll C-84 has become the product of choicefor applications such as bonding polyurethane foam which needs high wet bond strength. Dispercoll C-74 is being used inbonding high pressure laminate to particle board which requires good heat resistance along with a contact bond life ofmore than one hour. Dispercoll C LS 2372H has found its niche in formulations which are designed to have high tack andalso the ability to be repositioned. Other applications for Dispercoll C polychloroprene latices are footwear, mill work andDIY. Dispercoll C polychloroprene latices have the same chemical structure as Baypren polycloroprenes; so they have thesame good weathering properties and chemical resistance.

Dispercoll C-74 C-84 C LS 2372H

Solids Content (%) 58 55 58

Viscosity (cps) 80 110 100

pH 13 13 13

Particle size (nm) 160 160 160

Crystallization tendency Medium Strong Low

Emulsifier Anionic Anionic Anionic

PropertiesDispercoll C-74, C-84 and LS 2372H polychloroprene latices are alkaline colloidal dispersions of 2-chlorobutadiene pro-duced by emulsion polymerization. Dispercoll C-74 is a medium crystallizing polymer. One can see from the film data thatthis gives relatively high elongation and long open time. Dispercoll C-84, on the other hand, is a strong crystallizing poly-mer. This results in high tensile strength and a shorter open time. Dispercoll C LS 2372H is a low crystalline with very longopen time and lower tensile strength. The differences in the softening points between these three products reflect differentmolecular weights.

Film Properties

Dispercoll C-74 C-84 C LS 2372H

Tensile Strength (psi) 500 2900 65

Elongation at break (%) 1000 760 1000

100% Modulus 120 580 60

Softening Point (°C) 82 61 50

Contact Bond Life

Pass 1 hour 30 72 hoursminutes

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ADHESIVE FORMULATINGCONTACT CEMENTS

Dispercoll C Latices are normally compounded with other ingredients - such as resins, zinc oxide, antioxidants, thickeners and stabilizers - to modify adhesion, rheological behavior, and improve wet stability and aging properties.Bayer has also introduced four grades of Dispercoll S silica dioxide sols which enhance the performance of Dispercoll Cpolychloroprene latices.

ResinsResins improve the adhesion of Dispercoll C based adhesives to many substrates and affect their open times. InBayer's early screening studies it was observed that a tackifier level of 20 phr did not change the peel strength of theformulation. Levels of 35 and 50 phr gave a good bond strength and contact bond life values. A resin level of 65 phrdecreased the peel strength because of a loss of adhesion between the two adhesive films. The tackifying resins mostwidely used in water based formulating are dispersions of terpene phenolic resins, rosin esters, coumarone-indeneresins, or hydrocarbon resins. Terpene phenolic resins are known to give improved heat resistance, but usually shortenopen time. Rosin ester types are known for their good tack characteristics, but average heat resistance. The differencein contact bond life can be seen in the following graph. Several resin manufacturers supply terpene phenolic and rosinester resins in dispersion form. Because each commercial resin dispersion has its own surface active ingredients thatmay or may not be compatible with a particular grade of Dispercoll C latex, the emulsion stability and adhesive proper-ties of each formulation should be evaluated.

Examples of Commercial Resin Dispersions which are compatible with Dispercoll C products.

Supplier Name Resin Type

Schenectady HRJ 11112 Terpene phenolicDRT Dermulsene TR501 Terpene phenolic

Dermulsene TR602 Terpene phenolicEastman Tacolyn 5002 Aromatic modified hydrocarbon

Tacolyn 5003 Aromatic modified hydrocarbonTacolyn 3185 Rosin esterTacolyn 3400 Rosin ester

Arizona Aquatac 6085 Rosin esterAquatac E5375 Rosin ester

The following chart shows the effect of different types of resins on open time.

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Surfactant Type Supplier

Daxad 11KLS Anionic GEO Specialty Chemicals

Igepal CO 710 Nonionic Stepan Chemicals

Igepal CA 630 Nonionic Stepan Chemicals

Rhodaplex CO 433 Anionic Rhodia Surfactants

Triton X-100 Nonionic Dow Chemical

Emulvin W Nonionic Lanxess

Acid ScavengerZinc oxide serves as a stabilizer by neutralizing the minute amounts of hydrogen chloride which are split off from thepolymer as it ages. Elevated temperatures also cause the evolution of hydrogen chloride and destabilization of the latexemulsion. Typically 2 to 5 parts by weight of Zinkoxyd Aktiv, precipitated zinc oxide, on a hundred parts of polychloro-prene polymer are added to the formulation as an aqueous dispersion.

AntioxidantsAntioxidants are primarily used in polychloroprene based adhesives to protect the tackifying resin that is used in com-pounding. Those resins that are sensitive to oxidation, e.g. rosin esters and coumarone-indene, may become brittle dueto aging and cause bond failure. A hindered phenolic antioxidant, such as Vulkanox BKF, is recommended to help prevent this oxidative attack.

Both zinc oxide and antioxidants are commercially available as dispersions. The following table details dispersions fromtwo different suppliers.

Manufacturer ZnO Dispersion Antioxidant Dispersion

AkroChem W-9804 W-9924

Akron Dispersions Bostex 422 Bostex 346

SurfactantsSurfactants can be used to improve the compatibility of the various compounding ingredients. Nonionic surfactants canbe used to reduce the tendency to coagulate at low pH values. Surfactants can also be used to improve the mechanicalstability during high shear conditions. Both anionic and nonionic surfactants have been to be useful with Dispercoll Cproducts. It should be noted that too much of an emulsifying agent can have a negative effect on the properties of theadhesive by decreasing moisture resistance or interfering with the contact properties.

Examples of compatible surfactants.

ThickenersThickeners are used in water based systems for a variety of reasons. The most common is to increase the viscosity ofthe finished adhesive to provide enough sag resistance to prevent the wet film from flowing off the substrates.Thickeners can also aid in the suspension of pigments, fillers or metal oxides such as zinc oxide. Higher viscosity willprevent additives, which are heavier than the latex, from readily settling out.

The types of thickeners which have commonly been used for water based adhesives are polyvinyl alcohols, polyacry-lates, alginates and methylcellulose. Associative thickeners based on acrylates and urethanes are a class of thickenerswhich are now widely used. Rohm & Haas manufactures Acrysol RM-8W associative thickener, which has been foundto work well with Dispercoll C-74 and C-84 based formulations. It provides stable viscosity and uniform texture.

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Dispercoll S Solids % Density (g/cm3) Surface (m2/g) Diameter (nm)

S 5005 50 1.39 50 55

S 4510 45 1.34 100 30

S 4020 40 1.295 200 15

S 3030 30 1.208 300 9

Dispercoll SBayer has developed a series of Silica Sols, which are nano-particulate sized silica dioxide dispersed in an aqueousmedium. These silica sols are produced from a sodium silicate dispersion through a process that removes the sodiumto a minute level and then builds the molecular weight that is best for long term dispersion stability. These productshave been found to improve the adhesive properties of Dispercoll C polychloroprene latices. They can be used to modify viscosity, contact bond life, softening point, act as an acid scavenger and provide wet bond strength.

Formulas with high levels of Dispercoll S 3030 silica sol have shown very good wet bond strength. However in bondinghigh pressure laminate to particle board, experiments indicate that levels in the 5 to 15 phl range are better for adhesionto the substrates. These levels still show improvements in contact bond life and heat resistance. Each grade ofDispercoll S gives a different viscosity at a defined quantity. The smaller the particle size Dispercoll S grades show higher viscosities.

FORMULATIONS

The following suggested starting formulations are design to address specific performance requirements. These formulations are based on Dispercoll C/resin combinations known to be compatible. Each adhesive manufacture should test this and adjust according to their needs.

HIGH INITIAL BOND STRENGTHC-84/TR 85/S3030

FORMULATION Wet SolidsWeight Content

INGREDIENTS

Dispercoll C-84 Latex 100.0 55%

Desmulsene TR 602 Resin 15.0 55%

Dispercoll S 3030 SiO2 10.0 30%

ZnO2 Dispersion HCl scavenger 4.0 33%

Vulkanox Dispersion Antioxidant 2.0 50%

Open time 4 hours

Softening point 69°C

Viscosity 3640 cps

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HIGH HEAT RESISTANCE

FORMULATION Wet SolidsWeight Content

INGREDIENTS

Dispercoll C-74 Latex 100.0 58%

Emulvin W Surfactant 2.0 20%

Schenectady HRJ 11112 Tackifier 30.0 43%

ZnO2 HCl scavenger 4.0 33%

Vulkanox Dispersion Antioxidant 2.0 50%

Optional Ingredients:

Dispercoll S, Defoamer, Thickener

LONG CONTACT BOND LIFE

FORMULATION Wet SolidsWeight Content

INGREDIENTS

Dispercoll C-84 Latex 100.0 55%

VTAC 9001 Resin 15.0 55%

Dispercoll S 3030 SiO2 10.0 30%

ZnO2 Dispersion HCl scavenger 4.0 33%

Vulkanox Dispersion Antioxidant 2.0 50%

Open time 7 hours

Softening point 66°C

Viscosity 5100 cps

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WET BONDING (Textile)

FORMULATION Wet SolidsWeight Content

INGREDIENTS

Dispercoll C-84 Latex 100.0 55%

Dispercoll S 3030 SiO2 30.0 30%

ZnO2 Dispersion HCl scavenger 4.0 33%

Vulkanox Dispersion Antioxidant 2.0 50%

Optional Ingredients: Defoamer, Colorant

LOW ENERGY SURFACES

FORMULATION Wet SolidsWeight Content

INGREDIENTS

Dispercoll C LS 2372H Latex 100.0 58%

Emulvin W Surfactant 2.0 20%

Tacolyn 3185 Tackifier 30.0 55%

ZnO2 Dispersion HCl scavenger 4.0 33%

Vulkanox Dispersion Antioxidant 2.0 50%

Optional Ingredients: Defoamer, Thickener

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FOAM TO FOAM BONDING

2-Component Adhesive

For the bonding of foams in the manufacture of upholstered furniture and mattresses, adhesives containing chlorinatedsolvents have historically been used. With the introduction of regulations on the use of chlorinated solvents, it becamenecessary to eliminate adhesives containing 1,1,1-trichloroethane. One of the technologies which has gained wideacceptance is the use of 2 component polychloroprene latex based adhesives.

The basic principle of a 2 component polychloroprene adhesive is the destabilization of the latex emulsion by a salt orweak acid. This principle has been used in the manufacture of latex gloves for many years. The utilization of this behav-ior for adhesives was made possible by the development of spray guns that delivers both the adhesive and salt solutionsimultaneously from separate delivery nozzles. The spray gun atomizes both the adhesive and the salt into the sprayzone. Coagulation of the latex occurs in the aerosol phase before it hits the substrate. Because the adhesive has beencoagulated it has the necessary green strength to immediately bond the foam substrates together. The water that ispresent in the adhesive film is absorbed by the substrate and eventually evaporates over a period of time.

The effective utilization of thistechnology is dependent on theproper adjustment of the sprayequipment. Salts like calcium chlorideare dissolved into water at a 5% level.The salt solution is placed in thesecond of two storage pots that a2-component spray gun systemcontains. Each pressure pot has itsown pressure and delivery adjustments.A typical fluid delivery ratio is 100 mlof adhesive to 10 ml of salt solution.Differences in the solution concentrationor utilized salt may vary the mix ratio.

A two component foam adhesive contains the same ingredients as the typical water based polychloroprene adhesive.Resins are added to modify tack. The type of resin dispersion will influence the heat resistance properties. Because thecoagulation behavior of the polychloroprene is the key to the success of these adhesives the resin normally only addedat a level of 20 to 30 parts on 100 latex. Surfactants can be used to modify the mechanical stability of the adhesive.Zinc oxide and antioxidants are added in disperse form to aid in the aging stability of the adhesive bond. Sometimeswetting agents or defoamers are employed.

Internal foam block

upper foam

foam for construction of box

foam with adhesive

Bonding of seating using 2K spray mix process with Dispercoll C

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2K FORMULATION

FORMULATION Wet SolidsWeight Content

INGREDIENTS

Dispercoll C-84 Latex 100.0 55%

Emulvin W Surfactant 2.0 20%

Dermulsene TR 602 Tackifier 30.0 50%

ZnO2 Dispersion HCl scavenger 6.0 33%

Vulkanox Dispersion Antioxidant 2.0 50%

Coagulation Agent:

5% solution of salt (e.g. CaCl2 or Zn SO4)

Mix ratio 10:1

Optional Ingredients: Defoamer

The following figures show that the potassium counter ion associates with the soap used in the emulsion polymeriza-tion. When the latex is co-sprayed with a salt solution the counter ion is pulled away from the emulsion boundary andcoagulation occurs.

Salt Destabilization

CI CI

CI

CICI

CI

CI CI

CI

-

--

-

--

-

- -

PolymerPolymer

Normal CR Micelle

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1-Component AdhesiveMore recently, one component foam adhesives have become popular because it is not necessary to adjust mix ratiosbetween the latex/resin “Part A” and the salt solution. To make the adhesive coagulate (break) upon spraying it is nec-essary to adjust the pH down to the point where the latex is barely stable. This can be done with glycine or dilutehydrochloric acid. The challenge of a 1-component formulation is to avoid coagulating the adhesive before it is sprayed.If the pH is adjusted too low the latex will coagulate in the container. If the pH is too high, spraying will not cause coag-ulation. Each ingredient that is added to the formulation can affect the emulsion stability. Also these types of systemstend to have shorter shelf lives because the natural downward pH drift of polychloroprenes will bring the adhesive clos-er to its coagulation point. The following is a basic starting point formulation for a one component foam adhesive.

ONE COMPONENT FOAM ADHESIVE

FORMULATION Wet SolidsWeight Content

INGREDIENTS

Dispercoll C-84 Latex 100.0 55%

Dermulsene TR 602 Tackifier 30.0 50%

ZnO2Dispersion HCl scavenger 6.0 33%

Vulkanox Dispersion Antioxidant 2.0 50%

pH Adjusting Agent

18% Glycine solution (to pH of 9.0 to 9.5)

Discretional Ingredients:

Surfactant and/or defoamer

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The following figure gives a representation of the emulsion state of Dispercoll C. On the left is represented a stable poly-chloroprene emulsion at a typical pH. In the figure below, the right section shows that by lowering the pH to less than9.5 the potassium counter-ion no longer closely associated with soap. This reduction of the counter charge on the soapemulsion reduces the tendency for the emulsion particles to come in contact with each other and coagulate. During thespraying process the latex is subjected to shear forces which cause it to coagulate into an adhesive film and be able tobond in a wet state.

Low pH Destabilization

Storage conditionsThe pH value of Dispercoll C polychloroprene latices tends to drop during prolonged storage, which can result inreduced stability. Bayer states that the shelf life of the Dispercoll C latices is six months. It is recommended that inventory be used on a first in first out basis to minimize the storage time of the latex. The recommended storage temperature range is 5 to 25°C which will minimize the risk of pH change. Temperatures above 25°C can be toleratedfor short periods of time. For example a temperature of 30°C is likely to reduce the pH of Dispercoll C-84 from 12.5 to12.0 in 4 weeks. A temperature of 50°C has been shown to reduce the pH 1.0 units in 7 days. To provide the best pHstability a temperature around 23°C is best.

Mixing Procedure

Water-based systems are sensitive to being destabilized by different pH levels or emulsification systems. The stability of the latices may be affected by the addition of compounding ingredients. During compounding, the addition of resindispersions normally will lower the pH of the finished adhesive. It is recommended that the pH value of the formulationbe readjusted to at least 10.5 (this is the pH at which there is no excess counter ion) to provide an acceptable shelf life.A 5% potassium hydroxide solution is recommended to increase pH. If surfactants are used in the formula, they areadded to the latex prior to the other compounding ingredients.

The order and technique of addition can be critical to a formulation. The general rule for order of addition is to start withthe largest amount and work to the smallest amount of ingredient. The exceptions are materials that add stability andcompatibility during the mixing process, i.e. defoamers and surfactants. Thickening agents are normally added last. Thecompounding ingredients should be added to mixture slowly with sufficient shear to help ensure a homogenous blend.

PolymerPolymer

Dispercoll C Micelle

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Health and Safety Information

Appropriate literature has been assembled which provides information concerning the health andsafety precautions that must be observed when handling Bayer products mentioned in this publica-tion. For materials mentioned that are not Bayer products, appropriate industrial hygiene and othersafety precautions recommended by their manufacturers should be followed. Before working withany product mentioned in this publication, you must read and become familiar with the availableinformation concerning its hazards, proper use, and handling. This cannot be overemphasized.Information is available in several forms, e.g., material safety data sheets and product labels.Consult your Bayer Representative acontact the Product Safety Manager within the Health,Environment, Safety and Plant Management Department, Bayer Corporation, 100 Bayer Road,Pittsburgh, PA, 15205-9741, (412) 777-2000.

The manner in which you use and the purpose to which you put and utilize our products, technical assistance and information (whetherverbal, written or by way of production evaluations), including any suggested formulations and recommendations are beyond our con-trol. Therefore, it is imperative that you test our products, technical assistance and information to determine to your own satisfactionwhether they are suitable for your intended uses and applications. This application-specific analysis must at least include testing to deter-mine suitability from a technical as well as health, safety, and environmental standpoint. Such testing has not necessarily been done byus. Unless we otherwise agree in writing, all products are sold strictly pursuant to the terms of our standard conditions of sale. All infor-mation and technical assistance is given without warranty or guarantee and is subject to change without notice. It is expressly under-stood and agreed that you assume and hereby expressly release us from all liability, in tort, contract or otherwise, incurred in connectionwith the use of our products, technical assistance, and information. Any statement or recommendation not contained herein is unautho-rized and shall not bind us. Nothing herein shall be construed as a recommendation to use any product in conflict with patents coveringany material or its use. No license is implied or in fact granted under the claims of any patent.

© Bayer MaterialScience LLC 06/05

Craig Jansen: 412-777-4893

[email protected]

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