WO2013131272A1

WO2013131272A1 - Primer composition for exterior insulation finish system

Info

Publication number: WO2013131272A1
Application number: PCT/CN2012/072117
Authority: WO
Inventors: Yanfeng Wu
Original assignee: Rohm And Haas Company
Priority date: 2012-03-09
Filing date: 2012-03-09
Publication date: 2013-09-12

Abstract

A primer composition used in exterior insulation finish system consisting of 2% to 6% by weight of aluminate cement, 0.8% to 4.5% by weight of calcium sulfate, 2.5% to 5% by weight of Portland cement, 25% to 40% by weight of polymer particles, wherein said polymer particles are provided in the form of a polymer emulsion, 35% to 55% by weight of fillers, 0 to 0.4% by weight of cellulose ether, 0 to 0.15% by weight of defoamer, 0 to 0.15% by weight of fibers, and 0 to 0.15% by weight of hydrophobic agent, with percents relative to total dry weight of the primer composition.

Description

PRIMER COMPOSITION FOR EXTERIOR INSULATION FINISH SYSTEM

FIELD

The present invention relates to a primer composition used in the construction industry. Particularly, the present invention relates to a cement based primer composition useful for a spray polyurethane foam (SPF) based Exterior Insulation Finish System (EIFS).

INTRODUCTION

An Exterior Insulation Finish System (EIFS) is an exterior wall cladding system, and is also known as External Thermal Insulation Composite Systems (ETICS) in Europe. It can be used on both residential and commercial buildings for the purpose of saving energy, improving room comfort and protecting walls against moisture and other external elements.

In a spray polyurethane foam (SPF) based EIFS, SPF is used as a thermal insulation layer and is considered to possess some advantages over other types of insulation layers, such as improved fire retardant performance. SPF also has lower thermal conductivity and therefore, has improved insulation ability compared with EPS and XPS boards. With these advantages, SPF used as the thermal insulation layer in an EIFS has become more and more popular.

When applied onto a wall substrate (or a leveling layer on a wall substrate if the leveling layer is present), SPF will form a continuous plastic face which is hard and smooth. Such face has a very low water absorption rate (normally less than 3%), and it is difficult to apply a basecoat mortar directly onto it. Traditionally, a polymer emulsion is used as a primer ("polymer emulsion primer") to improve adhesion between a mortar layer and a substrate. For example, JP2011208371 A, JP2010018488 A and WO2011060684 A disclose an acrylic type or a styrene acrylic type polymer emulsion used as primers in construction. A basecoat mortar (or other coating mortars) should be applied before the polymer emulsion is dry and therefore the permissible working time is limited. In addition, polymer emulsion is an organic material based product and such polymer emulsion primer generally does not help to improve the fire retardency of the overall EIFS.

A Chinese patent application having the publication number of CN101838132 A discloses a special interface treating mortar for SPF surfaces within an EIFS , which is a Portland cement containing mortar and further comprises calcium carbonate powder, silica sand, polymer emulsion, superplastizer, defoamer, wood fiber, hydrophobic agent, pH adjusting agent, cellulose ether and water. But such a Portland cement containing mortar has poor early bonding strength even an early strength agent is present, which will significantly postpone the whole working progress of EIFS construction.

It is desirable to provide a new primer for use within a SPF based EIFS that provides better early bonding strength as compared with a traditional interface treating mortar. It is even more desirable if such a new primer would be less flammable than current polymer emulsion primers.. SUMMARY

Inventors have identified a composition that can be easily applied to SPF as a primer ("primer composition"), that has desireable early bonding strength as required for EIFS application. Moreover, the primer composition is primarily (more than 50% by weight) inorganic materials and so it is expected to be less flammable than traditional polymer emulsion primers. Thus, such a primer composition is useful in construction as a primer layer to improve the adhesion between a basecoat mortar layer and an SPF face within an EIFS.

In a first aspect, the present invention provides a primer composition consisting of 2% to 16% by weight of aluminate cement, 0.8% to 4.5% by weight of calcium sulfate, 2.5%) to 15%) by weight of Portland cement, 25% to 40% by weight of polymer particles, wherein the polymer particles are provided in the form of a polymer emulsion, 35% to 55% by weight of fillers, 0 to 0.4% by weight of cellulose ether, 0 to 0.15% by weight of defoamer, 0 to 0.15% by weight of fibers, and 0 to 0.15% by weight of hydrophobic agent, with percents relative to total dry weight of the primer composition.

Preferably, calcium sulfate is provided from gypsum.

In a second aspect, the present invention provides an EIFS installed on a wall substrate comprising a spray polyurethane foam layer formed on the wall substrate, a basecoat mortar layer applied on the spray polyurethane foam layer, and a primer layer made of the primer composition of the first aspect of the present invention, wherein the primer layer is present between the spray polyurethane foam layer and the basecoat mortar layer.

In a third aspect, the present invention provides a process for installation of the EIFS according to the second aspect, comprising the steps of spraying polyurethane foam to form a foam layer on a wall substrate or on a leveling layer, if the leveling layer is present, applying the primer composition according to the first aspect of the invention onto the foam layer to form a primer layer, and applying a basecoat mortar onto the primer layer to form a basecoat mortar layer.

With the help of the inventive primer composition, the bonding strength between a

SPF face and a basecoat mortar layer in an EIFS can achieve an early bonding strength of more than 0.2 MPa at curing for one day, and can meet the EIFS requirements demanded within the industry, including China industrial code JG149-2003, "External Thermal Insulation Composite Systems Based on EPS", China national code GB50404-2007, "Technical Code for Rigid Polyurethane Foam Insulation and Waterproof Engineering", and European technical code ETAG 004-2000, "Guideline for European Technincal Approval of External Thermal Insulatioin Composite Systems with Rendering". After a primer layer made of the inventive primer composition is applied onto a SPF face, there is no limitation on the working time for a basecoat mortar appling onto the primer layer. Even if the primer layer applied on the SPF face has dried, a basecoat mortar can still be applied thereon and reach workable bonding strength under the related codes. Compared with those systems having traditional polymer emulsion primers, the EIFS having the inventive primer layer is expected to be less flammable due to the majority part of non-combustible inorganic materials included therein.

DETAILED DESCRIPTION

As used herein:

Unless otherwise stated, all percentages (%) are by weight based on the total dry weight of the primer composition.

The units/abbreviations used in the description are illustrated as follows.

Unit Full name

mm millimeter

MPa megapascal

mPa-s(i.e. centipoise, cp) milli-Pascal- second

Pa s Pascal- second

and/or "additionally, or as an alternative"

e.g. "for example" i.e. "that is to say"

"Aluminate cement" and "Portland cement" are widely used cements in the construction industry. Aluminate cement, also named "high alumina cement", is a water- hardening material have a fast early strength enhancing rate compared with Portland cement and sulfate aluminate cement. Aluminate cement comprises CA (CaOAl₂0₃) as its main component, while 3CaOSi0₂, 2CaOSi0₂, and C₃A (3CaOAl₂0₃) in Portland cement and C₄A₃S D (3CaO3Al₂0₃-CaS0₄) in sulfate alumina cement. According to China national code GB 201-2000 (stipulated by refering to Franch code F P 15-315: 1991, "Aluminate Cement", and Japanese code JIS R2511 : 1995, "Aluminate Cement for Refractories"), aluminate cement comprises at least 50% alumina (A1₂0₃), which is much higher than Portland cement (normally 2.5% to 6%) and is also higher than sulfate aluminate cement (normally 20% to 40%). About 50% to 80% alumina fraction exists as CA (CaOAl₂0₃) in aluminate cement, while CA is rarely present in Portland cement and sulfate aluminate cement. In addition, Sulfate is rarely present in aluminate cement, while Portland cement comprises about 3.0% (calculated as sulfur trioxide) and sulfate aluminate cement about 10%) (calculated as sulfur trioxide). The content of sulfate in different cements could be measured by gravimetric analysis of barium sulfate and expressed as sulfur trioxide

(reference method following China national code GB/T 176-2008, "Chemical Analysis Methods of Cements", or the international standard, ISO 29581-1(2009), "Cement-Test Methods-Analysis by Wet Chemistry").

Referring to China national code GB 201-2000, aluminate cement is classified into four categories based on alumina content, CA-50 having an alumina content of between 50% and 60%, CA-60 between 60% and 68%, CA-70 between 68% and 77%, and CA-80 larger than 77% by weight based on the total dry weight of the cement. Preferably, the inventive primer composition comprises CA-50 and/or CA-60 aluminate cement.

In the inventive primer composition, aluminate cement is used together with

Portland cement and gypsum to form a cementitious system. Aluminate cement has much better early strength than Portland cement and sulfate aluminate cement. The cementitious system can afford both higher early strength and acceptable longer term strength in the inventive primer composition than traditional cementitious materials.

In one aspect, if aluminate cement is present in a lower content, such as less than 2%, the inventive primer composition may have poor early bonding strength, such as lower than 0. IMPa at curing for one day. In another aspect, if a higher content, such as more than 16%, the inventive primer composition may harden too fast (such as less than 0.5 hour) and therefore working time is very limited. The inventive primer composition typically comprises 2% or more, and can comprise 5% or more, even 8% or more, and at the same time typically comprises 20% or less, and can comprise 16% or less, even 13% or less by weight of aluminate cement based on the total dry weight of the primer composition.

In one aspect, if Portland cement is present in a lower content, such as less than 2.5%), the bonding strength development of inventive primer composition may not meet the requirement under China industrial code JG149-2003, China national code GB50404-2007, and European technical code ETAG 004-2000. In another aspect, if a higher content, such as more than 15%, the early bonding strength may be poor, such as lower than 0. IMPa at curing for one day. The inventive primer composition typically comprises 2.5% or more, and can comprise 3% or more, even 4% or more, and at the same time typically comprises 15%) or less, and can comprise 10% or less, even 8% or less by weight of Portland cement based on the total dry weight of the primer composition. Preferably, the inventive primer composition comprises Portland cement having a strength grade of 42.5R or higher under China national code GB 175-2007, "Common Portland Cement" (stiplulated by referring to European code ENV197- 1 :2000, "Common Portland Cement" ).

Calcium sulfate can be used to control the setting time of cementitious materials. It can react with C₃ A (tricalcium aluminate) and Ca(OH)₂ in Portland cement to prevent hydration of C₃A and will eventually prolong the setting time of the cement, which increases the working time of the inventive primer composition. Gypsum is powder of calcium sulfate crystal and a very soft mineral mainly composed of hydrated calcium sulfate with the chemical formula CaS0₄-nH₂0, for example dihydrated gypsum, anhydrate gypsum and semi-hydrated gypsum.

In one aspect, too much calcium sulfate, such as present in a content of more than 4.5%), may cause excessive expansion and result in expansive cracks in the structure. Such expansion and cracks could lead to detachment and fragmentation of a primer layer made of the inventive primer composition in an EIFS. So the content of calcium sulfate should be limited. In another aspect, less calcium sulfate, such as less than 0.8%, may result in the inventive primer composition hardening too fast (such as less than 0.5 hour) and therefore the working time is very limited. The inventive primer composition typically comprises 4.5%) or less, and can comprise 4% or less, even 3.5% or less, even further 3% or less and at the same time typically comprises 0.8% or more, and can comprise 1.5% or more, even 2.5%) or more by weight of calcium sulfate based on the total dry weight of the inventive primer composition.

Fillers are inorganic material without binding function. They include coarse aggregates and fine fillers. The coarse aggregates used in the inventive primer composition can have a particle size in a range of from 40 mesh to 140 mesh (0.36mm to 0.11mm). The particle size of fine fillers is small, generally less than 0.1mm. Preferably, the fine fillers used in the inventive primer composition have a particle size of less than 200 mesh

(0.075mm). One example of coarse aggregates is quartz sand, while preferably, fine fillers can be rock powders, such as calcium carbonate, talc or dolomite powders. Quartz sand generally refers to all sorts of sand with quartz content at an absolute high level (at least 90%)), such as sea sand, fluvial sand and lake sand.

Fillers play a role of backbones in the inventive primer composition. In one aspect, if fillers are present at a higher content, such as more than 55%, the bonding strength may be poor to meet the requirement of related code, such as China industrial code JG149-2003, and the primer composition cannot be applied onto a thermal insulation layer by roller coating. In another apect, if fillers are present at a lower content, such as less than 35%, the inventive primer composition may tend to produce expansive cracks in the primer layer. The inventive primer composition typically comprises 35% or more, and can comprise 40% or more, even 45% or more, and at the same time typically comprises 55% or less, and can comprise 52% or less, even 50% or less by weight of fillers based on the total dry weight of the inventive primer composition.

Polymer emulsion is a two-phase system having finely dispersed polymer particles in solvent, such as water. The polymer particles can be homopolymers, copolymers or terpolymers of one or more monomers selected from the group consisting of styrene, butadiene, vinyl acetate, versatate, propionate, laurate, vinyl chloride, vinylidene chloride, ethylene, and acrylates, e.g., ethylene/vinylacetate copolymer (vinyl ester-ethylene copolymer), vinylacetate/vinyl- versatate copolymer, and styrene/acrylic copolymer.

Preferably, the polymer particles of the polymer emulsion in the inventive primer composition are provided from acrylic polymer, such as a copolymer of methyl

methacrylate and butyl acrylate. One example of polymer emulsion is PRIMAL™ APR- 968LO available from The Dow Chemical Company (PRIMAL is a trademark of The Dow Chemical Company). Polymer particles provided in the form of a polymer emulsion are used as a polymeric binder to improve the bonding strength of a primer layer made of the inventive primer composition with a SPF face. A higher concentration of polymer particles in the primer composition, that is more than 40% by weight of polymer particles based on the total dry weight of the inventive primer composition, may lead to the inventive primer composition shrinking too much and therefore tending to cause cracking. A lower concentration of polymer particles, that is less than 25% based on the total dry weight of the inventive primer composition, may lead to the inventive primer composition having insufficient bonding strength and also tending to cause cracking. The inventive primer composition typically comprises 25% or more, and can comprise 28% or more, even 30% or more, and at the same time typically comprises 40% or less, and can comprise 38% or less, even 35% or less by weight of polymer particles in the primer composition based on the total dry weight of the inventive primer composition.

Other additives could be optionally used in the inventive primer composition, for example, cellulose ether, defoamer, hydrophobic agent, and polymer fibers.

Cellulose ether is used for water retention and improvement of workability in the inventive primer composition, such as hydroxyethylmethylcellulose (HEMC),

Hydroxypropylmethylcellulose(HPMC), hydroxyethylcellulose (HEC),

hydroxypropylcellulose (HPC), hydroxypropylhydroxyethylcellulose (HPHEC) and carboxymethylcellulose (CMC). The inventive primer composition typically comprises zero or more, and can comprise 0.1% or more, even 0.2% or more, and at the same time typically comprises 0.5% or less, and can comprise 0.4% or less, even 0.3% or less by weight of cellulose ether based on the total dry weight of the inventive primer composition.

Defoamer, also named anti-foam agent, is used to reduce and hinder the formation of foam upon mixing the components of the inventive primer composition together with water. Defoamer can be selected from the group consisting of mineral oil, synthetic oil, silicone, organic modified silicone, polyglycol and molecular defoamer. Preferably, the defoamer used in the inventive primer composition is fatty acid ester of polyether. The inventive primer composition typically comprises zero or more, and can comprise 0.02% or more, even 0.05% or more, and at the same time typically comprises 0.15% or less, and can comprise 0.12% or less, even 0.1% or less by weight of defoamer based on the total dry weight of the inventive primer composition. Hydrophobic agent is water repellant material incorporated into hydratable cementitious materials such as cement pastes, masonry cements, mortars, and concrete to achieve a degree of moisture impermeability. Preferably, the hydrophobic agent in the inventive primer composition is silane-based. Silane-based hydrophobic agents are silanes that are chemical compounds of silicon and hydrogen and consist of a chain of silicon atoms covalently bonded to each other and to hydrogen atoms. For example,

butyltrimethoxysilane and other silanes are commercially available from Dow Corning and AkzoNobel and are suitable silane-based hydrophobic agents. The inventive primer composition typically comprises zero or more, and can comprise 0.02% or more, even 0.03% or more, and at the same time typically comprises 0.15% or less, and can comprise 0.1%) or less, even 0.06% or less by weight of hydrophobic agent based on the total dry weight of the inventive primer composition.

Fibers are used to enhance the flexibility of the inventive primer composition.

Preferably, polymer fibers, also named as synthetic fiber, are used in the inventive primer composition. More preferably, fibers are polypropylene fibers, such as the polypropylene fibers (for example, 6mm in length and 0.02mm to 0.03mm in diameter). The inventive primer composition typically comprises zero or more, and can comprise 0.02% or more, even 0.03% or more, and at the same time typically comprises 0.15% or less, and can comprise 0.1% or less, even 0.06% or less by weight of fibers based on the total dry weight of the inventive primer composition.

A dry-mix of the inventive primer composition could be obtained by mixing all powdery components together. For example, fillers (including silica sand and calcium carbonate) and other dry additives (such as cellulose ether, hydrophobic agent and fibers) are mixed together for 60 seconds and then mixed with aluminate cement, gypsum and Portland cement for another 60 seconds. Liquid mixture is obtained by mixing liquid components, such as polymer emulsion and defoamer, and water together. Upon application, the dry-mix could be added under stirring into the liquid mixture to obtain the inventive primer composition on jobsite. The water content in the final primer composition can be in a range of from 30% to 50%, preferably from 35% to 45%, by weight based on the total weight of the composition (water in polymer emulsion inclusive).

Upon construction, the inventive primer composition can be applied, preferably with a thickness of from 0.1mm to 0.4mm, such as by a brush or a roller, onto a spray polyurethane foam face and typically stands for 24 hours before a basecoat mortar is applied thereon.

Weathering testing method of bonding strength follows China national code JG149-

2003.

Example

A comparison test was designed for testing the bonding strength of two examples, an inventive primer composition and a comparative primer. The comparative primer is a Portland cement-containing interface treating mortar in which only Portland cement was present as cementitious material and calcium formate as early strength agent. Information of components used in the primers is listed in Table 1 as below.

Table 1 : Specification/model and producer of primer components

Ltd.

Note: trademark of The Dow Chemical Company.

The basecoat mortar used to prepare the sample panels comprises 28% 42.5R Portland cement, 8% calcium carbonate, 60.3% silica sand, 3.3% EVA(ethylene- vinyl acetate) redispersible powder, 0.1% Seal-80, 0.2% WALOCEL™CP1425 and 0.1% 6mm polypropylene fibers by weight based on the total dry weight of the basecoat mortar.

The formulations of different primers and test result are shown in Table 2 as below.

Table 2: Primer formulation (part by weight) and comparison test result (values are in units as indicated)

In Table 2, "Rupture occurred in SPF board (partially)" means breakage partially occurred within the SPF board. "Rupture occurred in SPF board (fully)" means all of breakage occurred within the SPF board. "Rupture occurred between primer and SPF board" means breakage occurred between the primer layer and the SPF face, i.e. at the interface.

Under China national codes JG149-2003 and GB50404-2007, both dry bonding strength and wet bonding strength should be 0. IMPa or higher, and rupture should not occur at the interface. Under European code ETAG004-2000, the bonding strength after weathering test should be 0.08MPa or higher, or if lower than 0.08MPa, rupture should occur in the insulation board. It can be seen from Table 2 that the inventive example gave higher bonding strength than the comparative example in all tests. The inventive example achieved an early bonding strength after curing for only one day meeting the requirements under the China national codes and the European code. Although meeting the European code, the comparative example did not meet the China national codes upon curing for one day since rupture occurred at the interface. At the same time, the dry bonding strength after curing for 14 days and the wet bonding strength of the inventive example also met the requirements of the China national codes. Although meeting the European code regarding the wet bonding strength, the comparative example did not meet the requirement under the China national codes.

Claims

WHAT IS CLAIMED IS:

1. A primer composition, useful in an exterior insulation finish system, said primer composition consisting of

a) 2% to 16% by weight of aluminate cement,

b) 0.8% to 4.5% by weight of calcium sulfate,

c) 2.5% to 15%) by weight of Portland cement,

d) 25% to 40%) by weight of polymer particles, wherein said polymer particles are provided in the form of a polymer emulsion,

e) 35% to 55% by weight of fillers,

f) 0 to 0.4% by weight of cellulose ether,

g) 0 to 0. 15%) by weight of defoamer,

h) 0 to 0. 15%) by weight of fibers, and

i) 0 to 0. 15%) by weight of hydrophobic agent,

with percents relative to total dry weight of said primer composition.

2. The primer composition of Claim 1 , wherein said aluminate cement comprises from 50%o to 68% by weight of alumina based on the total weight of said aluminate cement.

3. The primer composition of Claim 1 , wherein said calcium sulfate is provided from gypsum.

4. The primer composition of Claim 1 , wherein said polymer particles are provided from acrylic polymer emulsion.

5. The primer composition of Claim 1 , wherein said primer composition consists of a) 2% to 16%) by weight of aluminate cement,

b) 0.8% to 4.5%o by weight of calcium sulfate,

c) 2.5%o to 15%o by weight of Portland cement,

d) 25%o to 40%o by weight of polymer particles, wherein said polymer particles are provided in the form of a polymer emulsion,

e) 35% to 55% by weight of fillers,

f) 0 to 0.4%) by weight of cellulose ether, and

g) 0 to 0. 15%o by weight of defoamer,

with percents relative to total dry weight of said primer composition.

6. The primer composition of Claim 5, wherein said primer composition consists of: a) 8% to 13% by weight of aluminate cement,

b) 2.5% to 3.5%) by weight of calcium sulfate,

c) 3%) to 8%) by weight of Portland cement,

d) 30%) to 35%) by weight of polymer particles, wherein said polymer particles are provided in the form of a polymer emulsion,

e) 40% to 50% by weight of fillers,

f) 0.2%) to 0.3%) by weight of cellulose ether, and

g) 0.05% to 0.1% by weight of defoamer,

with percents relative to total dry weight of said primer composition.

7. An exterior insulation finish system installed on a wall substrate comprising a) a spray polyurethane foam layer formed on said wall substrate or a leveling layer if said leveling layer is present,

b) a basecoat mortar layer applied on said spray polyurethane foam layer, and c) a primer layer made of said primer composition according to Claim 1, wherein said primer layer is present between said spray polyurethane foam layer and said basecoat mortar layer.

8. The exterior insulation finish system of Claim 7, wherein said primer layer is present with a thickness in a range of from 0.1mm to 0.4mm.

9. A process for installation of the exterior insulation finish system according to Claim 7, comprising the steps of

a) spraying polyurethane foam to form a foam layer on a wall substrate or on a leveling layer if said leveling layer is present,

b) applying the primer composition according to Claim 1 onto said foam layer to form said primer layer, and

c) applying a basecoat mortar onto said primer layer to form said basecoat mortar layer.