CA1268608A - Phenolic foam products and method of production - Google Patents
Phenolic foam products and method of productionInfo
- Publication number
- CA1268608A CA1268608A CA000539376A CA539376A CA1268608A CA 1268608 A CA1268608 A CA 1268608A CA 000539376 A CA000539376 A CA 000539376A CA 539376 A CA539376 A CA 539376A CA 1268608 A CA1268608 A CA 1268608A
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- Canada
- Prior art keywords
- foam
- fibrous
- froth
- insulation board
- core
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Casting Or Compression Moulding Of Plastics Or The Like (AREA)
Abstract
ABSTRACT
There is provided a method of preparing foam insulation products as well as such products in the form of eg. insulation boards. A polymer is initially pre-foamed (such as a phenolic polymer) and then placed in contact with a substrate surface where it then foams further. The substrate surface may be on one or both surfaces of the foam. In this way, good bonding to the substrate is achieved and excess material does not penetrate the substrate.
There is provided a method of preparing foam insulation products as well as such products in the form of eg. insulation boards. A polymer is initially pre-foamed (such as a phenolic polymer) and then placed in contact with a substrate surface where it then foams further. The substrate surface may be on one or both surfaces of the foam. In this way, good bonding to the substrate is achieved and excess material does not penetrate the substrate.
Description
This disclosure relates to insulation board or insula-tion products.
More particularly, to one aspect there is disclosed a me-thod of forming an insulation boar~ made of a phenol/formaldehyde foam; i.n another aspect, there is dlsclosed an insulation board product having a core of phenol/formaldehyde foam.
The use of foam ma-terials as insulation is known in the art. Many foam materials have different problems associa-ted with them-eg.flammability, the production of different types of gases on partial combustion, etc. all cause problems. Various attempts have been made to develop a :Eoam having an improved resistance to burning and at the same time, desirable insulation values.
Phenolic resins have been proposed in the past for producing flame-resistant foams. Such resins can be resoles produced by a base-cataly.zed copolymerization of phenol with an excess of formaldehyde.
A foamed phenolic resin, of itself, has limited application as an insulation board without being reinforced to provide added strength to the product.
One particular area of usefulness which phenolic foams could be developed for would be insulation panels or boards, as phenolic foams for this purpose can have high
More particularly, to one aspect there is disclosed a me-thod of forming an insulation boar~ made of a phenol/formaldehyde foam; i.n another aspect, there is dlsclosed an insulation board product having a core of phenol/formaldehyde foam.
The use of foam ma-terials as insulation is known in the art. Many foam materials have different problems associa-ted with them-eg.flammability, the production of different types of gases on partial combustion, etc. all cause problems. Various attempts have been made to develop a :Eoam having an improved resistance to burning and at the same time, desirable insulation values.
Phenolic resins have been proposed in the past for producing flame-resistant foams. Such resins can be resoles produced by a base-cataly.zed copolymerization of phenol with an excess of formaldehyde.
A foamed phenolic resin, of itself, has limited application as an insulation board without being reinforced to provide added strength to the product.
One particular area of usefulness which phenolic foams could be developed for would be insulation panels or boards, as phenolic foams for this purpose can have high
2~ insul.ation and other properties which are quite useful for this purpose. However r a problem has existed in that reinforcement by conventional prior art techniques is not suitable or appropria-te; this will be evident from the fact that when liquid compositi.ons from which such foam products are prepared, are placed on a reinEorcing substrate, they may "leak" through the substrate resulting in reduc:tion in yield of foam and sticking to or fouling of conveyor systems used in processing the foami.ng material.
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This is thought to occur since -the substra-tes or Eoam Eacings can be of various types of material such as a fibrous mesh, non-woven fabric, asbes-tos, or other natural or synthetic Eibrous sheet material, can have an open weave or pore system- and conventionally, it has been typical to pour -the liquid foamable material directly on-to the substrate while permit-ting the polymer to Eorm insltu.
Thus, the problems of leakage of the polymeric material through the substrate and/or core in the forma-tion of a Eoam product in which the substra-te is firmly bonded to the foam, has given rise to certain problems.
The problems of leakage of the polymeric material through the substrate and/or -the forma-tion of a foam product in which -the substrate is not firmly bonded to the foam are disadvantages which have existed.
In accordance with the teachings herein, there is provided a method of forming an insulation board or the-like, in which various types of substrates, of a fibrousnature, can be in-tegrally bonded to the foam by first oE
all initially fro-thing a foamable polymer, namely a phenolic polymer, bringing a substrate surface and the Eroth-Eoam into contact or juxtaposition with each other, permitting the frothed polymer to foam fur-ther, and subsequently curing the resulting foam product.
In conjunction with the above, there is also provided an insulation board or the like which has a core or layer of plastic foam of phenolic resin with facings or substrate and superstrate layers having fibrous material associated therewith so that the fibrous material and the foam are firmly bonded or -.
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attached toge-ther by virtue of -the :Eoam having been at least partially expanded while in contact with the substrate and superstrate layers so -that Eibers of the substra-te and supers-trate layers are imbedded in or secured by the foam to a sufficient degree to provide adhesion.
In greater de-tail of the above, by fro-th foaming the foamable phenolic resin, prior to depositing it on the substrate forming a part of the insulation board, elimination of much of the leakage of the polymer through the subs-tra-te material can be accomplished; at the same time, the superstrate layer is brought to contact with the expanding foam and by virtue of the Eibers thereof being in con-tact with expanding foam and a firm bond with the foam is formed when the latter is cured so that a reinforced insulation board can be achieved without the problems no-ted above.
According to a Eurther aspect of this invention there is provided a method for producing preferably continuously, an insulation board which has a rigid plastic foam core having two major surfaces and a facing ma-terial on at least one of the major surfaces, the method comprisingo (a) conveying a facing material along a production line, (b) depositing a partially expanded froth foam, which contains at least one blowing agent, on the facing material, the partially expanded froth foam comprising a mixture for forming a rigid polymer foam selected from the group consisting of phenolic polymer foam, and the blowing agent being easily vaporizable at atmospheric pressure, and (c) further expanding and curing the froth foam in ."
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contact with the facing material to form the insula-tion board.
In the above method, the inven-tion can also be for con-tinuously produclng an insulation board having fibrous layers on both major surfaces of a foam core by the steps of:
(a) conveying at least one lower fibrous layer along a produc-tion line, (b) depositing the partially expanded froth foam on the lower fibrous layer, (c) placing at least one advancing upper fibrous layer on the deposited, partially expanded froth foam to form an advancing sandwich of upper and lower fibrous layers and in-termediate froth foam, and (d) further expanding and curing -the froth foam in contact with the fibrous layers to form a rigid plastic foam core covered on both major surfaces with and penetrating interstices of the fibrous layers.
The above method can also be for continuously producing an insulation board having fibrous layers on both major surfaces of foam core by:
(a) conveying at least one lower fibrous layer along a production line, (b) deposi-ting the partially expanded froth foam on the lower fibrous layer, (c) placing at least on advancing upper fibrous layer on the deposited, partially expanded froth foam to form an advancing sandwich of upper and lower fibrous layers and intermediate froth foam, and (d) passing the sandwich through the nip of rotating rolls to meter the amoun-t of froth ~:
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foam and help it to penetrate the interstices of the Eibrous layers, and (e) -thereafter passing the sandwich :Erom the nip of the rotating rolls into a heated e~pansion zone, whereby the froth Eoam further expands and cures in contact with the fibrous layers to form a rigid plastic foam core covered on both major surfaces with and penetrating interstices of the fibrous layers.
A further aspect of this invention is directed to an insulation board comprising a core of rigid plastic foam having two major, substantially parallel surfaces and a facing material on at least one of the major surfaces of the core, the foarn core being formed in accordance with the above method by further expanding a partially expanded froth foam.in contac-t with the facing material, wherein the cells of the resulting foam core contain the volatile blowing agent employed in the method.
The above insulation board can also comprise a core : of rigid plastic foam having two major, substantially parallel surfaces and at least one fibrous layer on each of the major surfaces the interstices of which are penetrated by the foam.
~he above phenolic resins have been found to form a : preferred class of resins :~or use in the method and product described herein. It is possible that other resins with similar characteristics can be employed which may be considered by those skilled in the art to-be equivalent to a polyurethane~ a polyisocyanurate, a polyester and an epoxide polymer.
In a preferred form of the method for producing the ; ~ insulation board, the substrate layer with the fibrous ; material can be moved in a given direction; thereafter the partially e~panded foam can be placed in :
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juxtaposition wlth -the substrate layer, and if desired, a supers-trate layer (-thus Eorming a pair of opposed outer surEaces for -the insulation produc-t) can be placed in juxtaposition with the side of the foam opposed to the side where the first substrate layer is provided for thereafter, the resulting product can be passed between a pair of opposed fixed points- for example, it may be convenient to employ a conveyor carrying a substrate layer onto which the pre-foamed polymeric ma-terial is placed into juxtaposition with the substrate layer on the, a superstrate layer applied in juxtaposition with the pre-foamed material and -the resulting combination passed between a nip provided between a roller and -the conveyor. Other equivalent procedures may also be employed for -the same purpose-eg.
a nip defined be-tween two(2~ rollers, a double belt conveyor or shaper, or a series oE sheet metal mold in which the froth foam is laid.
The phenolic foam is one which is a resole foam derived from a composition comprising a phenolic resole with a formaldehyde to phenol mole ratio of from 1.2 :l to 2.5:1, a blowing agent - this may have a thermal conductivity less than 0.016 watts mC, and a surfactant and an acid catalyst. The foam may have a density of from 30 to 70 kg m3 and a closed-cell con-tent of at least 85%; the thermal conductivity of the foam after 100 days can be less than 0.02 watts mC and the value of ~k/ ~nt is less than 0.5 x 10-3 where ~k in watts/mC
is kloo minus kl and ~nt in days is lntloo minus lnt;
it may ha~e an isotropic pressure required to reduce the closed-cell content of the foam by a least 10 percent and in excess of 1.75 kg/cm2.
In one preferred form the resole from which the foam is prepared is essentially a convenkional ,, .
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phenol/Eormaldehyde resole preEerably with less -than 10%
by weigh-t of any ring-substituted phenolic components such as cresol, xylenol and the like. The F/P mole ratio of the resole is from 1.201 -to 2.5:1 though the ra-tios at the higher end of this range are not preferred hecause -the e~cessive amount of formaldehyde prolongs -the cure process. Ilowever if too small a ratio is used, complete reaction to Eorm the foam may be difficult to achieve. The most preferred F/P ratios are from 1.5 to 2.2:1. As used herein throughout7F/P ratio means the mole ratio of chemically combined Eormaldehyde to phenol in the resole. Such ratio can be determined by known procedures.
~ preferred form is from 30 to 70 kg/m3 but preferred foams have densities of from 40 to 60 kg/m3.
The densi-ty is obtained by cutting a core sample 3.6 cm in diameter and 2~9 cm in length; the core is weighed accurately and the densi-ty calculated.
The viscosity oE the preferred resole measured at room temperature oE 25C is from about 50,000 to 1,000,000 cps, with the best results obtained at a viscosity of from 80,000 to 600,000 cps and most preferably 80,000 to 300,000 cps. At such viscosities, the resole can be foamed to produce a substantially closed-cell foam using foaming conditions that are xelatively easily controlled. The activity of the resole is also very impor-tant since if it is too reactive the -temperature of the foaming composition rises too high with the result that water vapor uncontrollably blows the foam and control over density and closed-cell content is los-t. On the other hand, if reactivity time is too low processing -times are long and uneconomical. ~eactivity of a resole can be reduced by addition of water and can be increased by addition of ~ .
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more acid catalyst.
A resole is usually produced by -the conven-tional base-ca-talyzed reaction using an acid subsequent to Eormation of the resole to neutrali~e the base and stabilize the resin. This of course results in -the production of salt by the reaction of acid and base.
The resole may be neutralized using sulfuric acid or carbon dioxide to give large insoluble salt particles which can easily be filtered out beEore the resole is used to produce a Eoam. It may also be possible to use unEiltered resins if no settling problems are encountered in the foaming process employed. In general~ where salt particles are present, it is preferred that they be very large or very small, that is, subs-tantially larger in diame-ter than -that of the cell or smaller than the thickness of the cell wall. If smaller than -the cell wall thickness the particle will not adversely affect the window integrity whereas if larger than a cell the number of cells that are disrupted should be low. Resoles in which neutralization produces a soluble salt are usually not employed because of the water sensitivity such resoles oEten display in that the insula-ting properties and dimensional stability oE the resulting foam can be adversely affected by ambient humidity. However, resoles containing soluble salts which are not water sensitive, such as the calcium salt of an al~yl or aromatic sulfonic acid, or have low water sensitivity can be used.
A preferred option is the use o the so-called "dispersed-salt" resoles in which the neutralizing acid is oxalic acid and the oxalate salts formed are highly insoluble and in colloidal form with substantially no tendency to settle. These resins and foams made from ~2~
them are described for example in United States Patents Nos. 4,060,504 and 4,216,295.
qhe composi-tion from which the Eoam is prepared has a surfactant material in an amount suEEicient to form a foam which has cells with wlndows (the membranes between con-tiguous cells) that remain intact as the cell grows to its final size. The amount of surfac-tant tha-t can be used varies somewhat with the surfac-tant but in general it has been observed that closed-cell foams are difficult to achieve with less than 0.5% by weight of surfactant and that over 6.0~ by weight produces no advantage and may even be deleterious. The mos-t useful amoun-t of surfactant is found to be from 1 to 5% by weight. All surfactan-t percentages given are based on resole weight.
The surfactant can be any suitable compound for this purpose; these include, e.g., non-ionic surfactants such as polyethers, polyalcohols, particularly the condensation products of alkylene oxides with alkyl phenols, fatty acids, silanes and silicones, fa-tty acid esters of polyhydroxyl compounds such as sorbitan or sorbitol~ polysilyl phosphonates, polydimethylsiloxane and the capped surfactants described in United States Patent Nos. 4,133,931, 4,140,8~2 and 4,247,413O Ionic surfactants such as alkylated quaternary ammonium derivatives may also be used.
Foaming is catalyzed by an acid and any suitable product for this purpose may be used, e.g., those commonly used include boric acid, sulfuric acid and sulfonic acids such as toluene and xylene sulEonic acids. Other catalytic acids however are known in the art and may be used. ~he level of catalyst used in the foaming mixture may widely vary depending on the particular resole and catalyst used~ Levels between, : '' .
~ 3~0 e.g., abou-t 0.5 to e.g., 3.0 and preferably between 1.0 to 2.0 weight percent based on the weight oE the resole can be used.
Advan-tageously, the blowing agent has a thermal conductivity less than 0.016 and preferably less than 0.014 wa-tts/mC at ambient temperature to enhance the insula-tion value of the phenolic foam. Typicall~ this range includes blowing agents such as methylene dichloride, and various chlorofluoro-carbons such as monofluorotrichloromethane, difluorodichloromethane, monofluorodichloromethane, difluoromonochlorimethane, trifluorotrichloroethane, and tetraEluorodichloroethane.
"Freon 114", (1,2 dichlorotetrafluoroethane available from DuPont Company under the above trade mark) is par-ticularly preferred. The level of blowing agent used in the foaming mixture is dependent on the molecular weight of -the blowing agent and the density of the foam.
Levels between e.g., about 5 to about e.g. 25 and preferably between 10 to 20 weight percent for Freon 114 based on the weight of the resole can be used for foams of about 30 to 70 kgjm3.
In addi-tion to the components described above, the Eoam can further comprise other additives such as anti-punking additives and particulate or fibrous fillers such as glass fibers, talc and the like, to improve the Eire safety or physical characteristics of the resulting foam.
It may also comprise components added after the resole formation such as lignin materials, urea, or melamine as extenders or formaldehyde scavengers.
Hydrated alumina is effective in increasing the closed-cell content and is therefore a desirable component of the foam.' The components of the Eoam are mixed at a temperature and pressure calculated to ensure rapid expansion at the extrusion head. The mixing can be carried ou-t in any device capable of giving effective, fine (less than 10 micron) and uniEorm dispersion of the blowing agent in the mix-ture. A suitable mixer device for this s-tage of the opera-tion is a high shear pin-type mixer with a short residence time such as an Oakes mixer. The preferred blowing agents are conven-tionally supplied under air or nitrogen pressure to the mixer.
From the mixer the foamable mixture si passed to an extrusion head. Expansion from the head is rapid and results in a stream of foaming material that is deposited on a substrate. The extrusion head may be in the form of a slit so as to lay down a continuous sheet of foam. In a preferred process however the extrusion head is a valved pipe that reciprocates transverse to the direc-tion of extrusion so as to lay down, on a moving substrate,m a con-tinuous ribbon of Eoam in parallel lines that coalesce as foaming proceeds. In a further preferred feature shaping members provide limitations to the expansion, result in the production of a uniform shaped board of the foamed resin and may be used to apply facing materials and enhance penetration of the Eoam into the in-terstices of fibrous facing materials.
As the foaming proceeds the foam is conventionally held at a constant temperature of about 60C. This is done by passing the sheet as it is formed through an oven maintained at that temperature such that, as it leaves the oven aEter about 20 minutes, it has solidified sufficiently to be cut into board pieces which may then be stored at 60C for 18 hours to advance the cure.
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~2 The product of the present invention may have one or both oE its major faces provided with a facing material, which may comprise cardboard, paper products such as "Kraft" paper, asphal-t/asbestos composites, aluminum foil, plastic material, glass Eiber shee-t ma-terial that may optionally be resin or asphalt impregnated, etc. ~he par-ticular covering material may, of course, vary in Eorming the insulation product and depending on its end use.
In carrying out the process, and to form the insulating product, a force may be applied duriny production to bring the upper or lower layers of the foam material into close con-tact with the foam, to aid in bonding. Such forces may be applied by various means including e.g., the use of compressive force such as to contacting the outer layers with rollers.
Also in carrying out the process, and by using a froth foaming of the resin prior to depositing it on the substrate, with subsequent expansion while on the substrate, the problems associated with the prior art can be overcomeO This results in an improved insulation board or the li]ce product in which there can be penetration of the froth Eoam into the fibrous layers of the substra-te material without seepage -through the substrate material. Also when tip and bottom Eacings are applied, the foam product basically forms a sandwich of the foam between the two facings of the insulation board. After the froth foam is deposited from the mixing head, further expansion can be controlled to provide foam of suitable densi-ty and thickness. Curing, after Einal expansion is then carried out.
The closed-cell content was measured by an air pycnometer using the technique described in ASTM D-2856 (Procedure C) to obtain open-cell content, the closed~
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cell content being 100 minus the open-cell content. The thermal conduc-t:ivity of the Eoam was measured using the technique described in ASTM C-518-76 on a sample wi-th a 2.54 cm thickness having at least 20.3 cms of width and length. The top face of the sample was at 32C and the bottom at 15.5C, thereby providing a mean temperature of 24C for the entire sample. A heat flow meter thermal conductivity ins-trumen-t constructed in accordance with such method and available as Rapid-K
Erom Dynatech R/D Co., 99 Erie St., Cambridge, Mass.
02139 was used.
The resole used in each example was dehydrated to below 3% by weight o:E water and bodied at 50-60C for a time sufficien-t to provide the desired viscosity which was measured using a srookfield Viscome-ter Model HsT.
Since viscosity varia-tion with temperature is significant a Brookfield Thermocell was used for the resoles of the examples following hereinafter which comprised a thermo container along with an SCR
controller r Model HT-64, an SC4-27 spindle and an HT-2 sample container. Measurements were made at 25C. All viscosi-ties given were obtained by this technique.
The burst pressure oE the cells oE any particular foam was determined by measuring the closed-cell content of a foam sample, then placing that sample in a pressure tube and applying a small incremental isotropic pressure. After being subjected to that pressure for five minutes the closed-cell content was remeasured.
The sample was then replaced in the tube and pressurized at a slightly higher isotropic pressure Eor five minutes before being measured for closed-cell content again.
This procedure was repeated at even higher pressures and a graph was plotted of closed-cell content against pressure. It was found that, at a characteristic . ~
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' ' iso-tropic pressure for each foam, the clo.sed-cell content dropped dramatically by at least 10~ and continued to drop thereafter. This pressure is called the "burst pressure".
Density was calculated from an accurately weighed
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This is thought to occur since -the substra-tes or Eoam Eacings can be of various types of material such as a fibrous mesh, non-woven fabric, asbes-tos, or other natural or synthetic Eibrous sheet material, can have an open weave or pore system- and conventionally, it has been typical to pour -the liquid foamable material directly on-to the substrate while permit-ting the polymer to Eorm insltu.
Thus, the problems of leakage of the polymeric material through the substrate and/or core in the forma-tion of a Eoam product in which the substra-te is firmly bonded to the foam, has given rise to certain problems.
The problems of leakage of the polymeric material through the substrate and/or -the forma-tion of a foam product in which -the substrate is not firmly bonded to the foam are disadvantages which have existed.
In accordance with the teachings herein, there is provided a method of forming an insulation board or the-like, in which various types of substrates, of a fibrousnature, can be in-tegrally bonded to the foam by first oE
all initially fro-thing a foamable polymer, namely a phenolic polymer, bringing a substrate surface and the Eroth-Eoam into contact or juxtaposition with each other, permitting the frothed polymer to foam fur-ther, and subsequently curing the resulting foam product.
In conjunction with the above, there is also provided an insulation board or the like which has a core or layer of plastic foam of phenolic resin with facings or substrate and superstrate layers having fibrous material associated therewith so that the fibrous material and the foam are firmly bonded or -.
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attached toge-ther by virtue of -the :Eoam having been at least partially expanded while in contact with the substrate and superstrate layers so -that Eibers of the substra-te and supers-trate layers are imbedded in or secured by the foam to a sufficient degree to provide adhesion.
In greater de-tail of the above, by fro-th foaming the foamable phenolic resin, prior to depositing it on the substrate forming a part of the insulation board, elimination of much of the leakage of the polymer through the subs-tra-te material can be accomplished; at the same time, the superstrate layer is brought to contact with the expanding foam and by virtue of the Eibers thereof being in con-tact with expanding foam and a firm bond with the foam is formed when the latter is cured so that a reinforced insulation board can be achieved without the problems no-ted above.
According to a Eurther aspect of this invention there is provided a method for producing preferably continuously, an insulation board which has a rigid plastic foam core having two major surfaces and a facing ma-terial on at least one of the major surfaces, the method comprisingo (a) conveying a facing material along a production line, (b) depositing a partially expanded froth foam, which contains at least one blowing agent, on the facing material, the partially expanded froth foam comprising a mixture for forming a rigid polymer foam selected from the group consisting of phenolic polymer foam, and the blowing agent being easily vaporizable at atmospheric pressure, and (c) further expanding and curing the froth foam in ."
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contact with the facing material to form the insula-tion board.
In the above method, the inven-tion can also be for con-tinuously produclng an insulation board having fibrous layers on both major surfaces of a foam core by the steps of:
(a) conveying at least one lower fibrous layer along a produc-tion line, (b) depositing the partially expanded froth foam on the lower fibrous layer, (c) placing at least one advancing upper fibrous layer on the deposited, partially expanded froth foam to form an advancing sandwich of upper and lower fibrous layers and in-termediate froth foam, and (d) further expanding and curing -the froth foam in contact with the fibrous layers to form a rigid plastic foam core covered on both major surfaces with and penetrating interstices of the fibrous layers.
The above method can also be for continuously producing an insulation board having fibrous layers on both major surfaces of foam core by:
(a) conveying at least one lower fibrous layer along a production line, (b) deposi-ting the partially expanded froth foam on the lower fibrous layer, (c) placing at least on advancing upper fibrous layer on the deposited, partially expanded froth foam to form an advancing sandwich of upper and lower fibrous layers and intermediate froth foam, and (d) passing the sandwich through the nip of rotating rolls to meter the amoun-t of froth ~:
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foam and help it to penetrate the interstices of the Eibrous layers, and (e) -thereafter passing the sandwich :Erom the nip of the rotating rolls into a heated e~pansion zone, whereby the froth Eoam further expands and cures in contact with the fibrous layers to form a rigid plastic foam core covered on both major surfaces with and penetrating interstices of the fibrous layers.
A further aspect of this invention is directed to an insulation board comprising a core of rigid plastic foam having two major, substantially parallel surfaces and a facing material on at least one of the major surfaces of the core, the foarn core being formed in accordance with the above method by further expanding a partially expanded froth foam.in contac-t with the facing material, wherein the cells of the resulting foam core contain the volatile blowing agent employed in the method.
The above insulation board can also comprise a core : of rigid plastic foam having two major, substantially parallel surfaces and at least one fibrous layer on each of the major surfaces the interstices of which are penetrated by the foam.
~he above phenolic resins have been found to form a : preferred class of resins :~or use in the method and product described herein. It is possible that other resins with similar characteristics can be employed which may be considered by those skilled in the art to-be equivalent to a polyurethane~ a polyisocyanurate, a polyester and an epoxide polymer.
In a preferred form of the method for producing the ; ~ insulation board, the substrate layer with the fibrous ; material can be moved in a given direction; thereafter the partially e~panded foam can be placed in :
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juxtaposition wlth -the substrate layer, and if desired, a supers-trate layer (-thus Eorming a pair of opposed outer surEaces for -the insulation produc-t) can be placed in juxtaposition with the side of the foam opposed to the side where the first substrate layer is provided for thereafter, the resulting product can be passed between a pair of opposed fixed points- for example, it may be convenient to employ a conveyor carrying a substrate layer onto which the pre-foamed polymeric ma-terial is placed into juxtaposition with the substrate layer on the, a superstrate layer applied in juxtaposition with the pre-foamed material and -the resulting combination passed between a nip provided between a roller and -the conveyor. Other equivalent procedures may also be employed for -the same purpose-eg.
a nip defined be-tween two(2~ rollers, a double belt conveyor or shaper, or a series oE sheet metal mold in which the froth foam is laid.
The phenolic foam is one which is a resole foam derived from a composition comprising a phenolic resole with a formaldehyde to phenol mole ratio of from 1.2 :l to 2.5:1, a blowing agent - this may have a thermal conductivity less than 0.016 watts mC, and a surfactant and an acid catalyst. The foam may have a density of from 30 to 70 kg m3 and a closed-cell con-tent of at least 85%; the thermal conductivity of the foam after 100 days can be less than 0.02 watts mC and the value of ~k/ ~nt is less than 0.5 x 10-3 where ~k in watts/mC
is kloo minus kl and ~nt in days is lntloo minus lnt;
it may ha~e an isotropic pressure required to reduce the closed-cell content of the foam by a least 10 percent and in excess of 1.75 kg/cm2.
In one preferred form the resole from which the foam is prepared is essentially a convenkional ,, .
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phenol/Eormaldehyde resole preEerably with less -than 10%
by weigh-t of any ring-substituted phenolic components such as cresol, xylenol and the like. The F/P mole ratio of the resole is from 1.201 -to 2.5:1 though the ra-tios at the higher end of this range are not preferred hecause -the e~cessive amount of formaldehyde prolongs -the cure process. Ilowever if too small a ratio is used, complete reaction to Eorm the foam may be difficult to achieve. The most preferred F/P ratios are from 1.5 to 2.2:1. As used herein throughout7F/P ratio means the mole ratio of chemically combined Eormaldehyde to phenol in the resole. Such ratio can be determined by known procedures.
~ preferred form is from 30 to 70 kg/m3 but preferred foams have densities of from 40 to 60 kg/m3.
The densi-ty is obtained by cutting a core sample 3.6 cm in diameter and 2~9 cm in length; the core is weighed accurately and the densi-ty calculated.
The viscosity oE the preferred resole measured at room temperature oE 25C is from about 50,000 to 1,000,000 cps, with the best results obtained at a viscosity of from 80,000 to 600,000 cps and most preferably 80,000 to 300,000 cps. At such viscosities, the resole can be foamed to produce a substantially closed-cell foam using foaming conditions that are xelatively easily controlled. The activity of the resole is also very impor-tant since if it is too reactive the -temperature of the foaming composition rises too high with the result that water vapor uncontrollably blows the foam and control over density and closed-cell content is los-t. On the other hand, if reactivity time is too low processing -times are long and uneconomical. ~eactivity of a resole can be reduced by addition of water and can be increased by addition of ~ .
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more acid catalyst.
A resole is usually produced by -the conven-tional base-ca-talyzed reaction using an acid subsequent to Eormation of the resole to neutrali~e the base and stabilize the resin. This of course results in -the production of salt by the reaction of acid and base.
The resole may be neutralized using sulfuric acid or carbon dioxide to give large insoluble salt particles which can easily be filtered out beEore the resole is used to produce a Eoam. It may also be possible to use unEiltered resins if no settling problems are encountered in the foaming process employed. In general~ where salt particles are present, it is preferred that they be very large or very small, that is, subs-tantially larger in diame-ter than -that of the cell or smaller than the thickness of the cell wall. If smaller than -the cell wall thickness the particle will not adversely affect the window integrity whereas if larger than a cell the number of cells that are disrupted should be low. Resoles in which neutralization produces a soluble salt are usually not employed because of the water sensitivity such resoles oEten display in that the insula-ting properties and dimensional stability oE the resulting foam can be adversely affected by ambient humidity. However, resoles containing soluble salts which are not water sensitive, such as the calcium salt of an al~yl or aromatic sulfonic acid, or have low water sensitivity can be used.
A preferred option is the use o the so-called "dispersed-salt" resoles in which the neutralizing acid is oxalic acid and the oxalate salts formed are highly insoluble and in colloidal form with substantially no tendency to settle. These resins and foams made from ~2~
them are described for example in United States Patents Nos. 4,060,504 and 4,216,295.
qhe composi-tion from which the Eoam is prepared has a surfactant material in an amount suEEicient to form a foam which has cells with wlndows (the membranes between con-tiguous cells) that remain intact as the cell grows to its final size. The amount of surfac-tant tha-t can be used varies somewhat with the surfac-tant but in general it has been observed that closed-cell foams are difficult to achieve with less than 0.5% by weight of surfactant and that over 6.0~ by weight produces no advantage and may even be deleterious. The mos-t useful amoun-t of surfactant is found to be from 1 to 5% by weight. All surfactan-t percentages given are based on resole weight.
The surfactant can be any suitable compound for this purpose; these include, e.g., non-ionic surfactants such as polyethers, polyalcohols, particularly the condensation products of alkylene oxides with alkyl phenols, fatty acids, silanes and silicones, fa-tty acid esters of polyhydroxyl compounds such as sorbitan or sorbitol~ polysilyl phosphonates, polydimethylsiloxane and the capped surfactants described in United States Patent Nos. 4,133,931, 4,140,8~2 and 4,247,413O Ionic surfactants such as alkylated quaternary ammonium derivatives may also be used.
Foaming is catalyzed by an acid and any suitable product for this purpose may be used, e.g., those commonly used include boric acid, sulfuric acid and sulfonic acids such as toluene and xylene sulEonic acids. Other catalytic acids however are known in the art and may be used. ~he level of catalyst used in the foaming mixture may widely vary depending on the particular resole and catalyst used~ Levels between, : '' .
~ 3~0 e.g., abou-t 0.5 to e.g., 3.0 and preferably between 1.0 to 2.0 weight percent based on the weight oE the resole can be used.
Advan-tageously, the blowing agent has a thermal conductivity less than 0.016 and preferably less than 0.014 wa-tts/mC at ambient temperature to enhance the insula-tion value of the phenolic foam. Typicall~ this range includes blowing agents such as methylene dichloride, and various chlorofluoro-carbons such as monofluorotrichloromethane, difluorodichloromethane, monofluorodichloromethane, difluoromonochlorimethane, trifluorotrichloroethane, and tetraEluorodichloroethane.
"Freon 114", (1,2 dichlorotetrafluoroethane available from DuPont Company under the above trade mark) is par-ticularly preferred. The level of blowing agent used in the foaming mixture is dependent on the molecular weight of -the blowing agent and the density of the foam.
Levels between e.g., about 5 to about e.g. 25 and preferably between 10 to 20 weight percent for Freon 114 based on the weight of the resole can be used for foams of about 30 to 70 kgjm3.
In addi-tion to the components described above, the Eoam can further comprise other additives such as anti-punking additives and particulate or fibrous fillers such as glass fibers, talc and the like, to improve the Eire safety or physical characteristics of the resulting foam.
It may also comprise components added after the resole formation such as lignin materials, urea, or melamine as extenders or formaldehyde scavengers.
Hydrated alumina is effective in increasing the closed-cell content and is therefore a desirable component of the foam.' The components of the Eoam are mixed at a temperature and pressure calculated to ensure rapid expansion at the extrusion head. The mixing can be carried ou-t in any device capable of giving effective, fine (less than 10 micron) and uniEorm dispersion of the blowing agent in the mix-ture. A suitable mixer device for this s-tage of the opera-tion is a high shear pin-type mixer with a short residence time such as an Oakes mixer. The preferred blowing agents are conven-tionally supplied under air or nitrogen pressure to the mixer.
From the mixer the foamable mixture si passed to an extrusion head. Expansion from the head is rapid and results in a stream of foaming material that is deposited on a substrate. The extrusion head may be in the form of a slit so as to lay down a continuous sheet of foam. In a preferred process however the extrusion head is a valved pipe that reciprocates transverse to the direc-tion of extrusion so as to lay down, on a moving substrate,m a con-tinuous ribbon of Eoam in parallel lines that coalesce as foaming proceeds. In a further preferred feature shaping members provide limitations to the expansion, result in the production of a uniform shaped board of the foamed resin and may be used to apply facing materials and enhance penetration of the Eoam into the in-terstices of fibrous facing materials.
As the foaming proceeds the foam is conventionally held at a constant temperature of about 60C. This is done by passing the sheet as it is formed through an oven maintained at that temperature such that, as it leaves the oven aEter about 20 minutes, it has solidified sufficiently to be cut into board pieces which may then be stored at 60C for 18 hours to advance the cure.
. .
.~
~2 The product of the present invention may have one or both oE its major faces provided with a facing material, which may comprise cardboard, paper products such as "Kraft" paper, asphal-t/asbestos composites, aluminum foil, plastic material, glass Eiber shee-t ma-terial that may optionally be resin or asphalt impregnated, etc. ~he par-ticular covering material may, of course, vary in Eorming the insulation product and depending on its end use.
In carrying out the process, and to form the insulating product, a force may be applied duriny production to bring the upper or lower layers of the foam material into close con-tact with the foam, to aid in bonding. Such forces may be applied by various means including e.g., the use of compressive force such as to contacting the outer layers with rollers.
Also in carrying out the process, and by using a froth foaming of the resin prior to depositing it on the substrate, with subsequent expansion while on the substrate, the problems associated with the prior art can be overcomeO This results in an improved insulation board or the li]ce product in which there can be penetration of the froth Eoam into the fibrous layers of the substra-te material without seepage -through the substrate material. Also when tip and bottom Eacings are applied, the foam product basically forms a sandwich of the foam between the two facings of the insulation board. After the froth foam is deposited from the mixing head, further expansion can be controlled to provide foam of suitable densi-ty and thickness. Curing, after Einal expansion is then carried out.
The closed-cell content was measured by an air pycnometer using the technique described in ASTM D-2856 (Procedure C) to obtain open-cell content, the closed~
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60~
cell content being 100 minus the open-cell content. The thermal conduc-t:ivity of the Eoam was measured using the technique described in ASTM C-518-76 on a sample wi-th a 2.54 cm thickness having at least 20.3 cms of width and length. The top face of the sample was at 32C and the bottom at 15.5C, thereby providing a mean temperature of 24C for the entire sample. A heat flow meter thermal conductivity ins-trumen-t constructed in accordance with such method and available as Rapid-K
Erom Dynatech R/D Co., 99 Erie St., Cambridge, Mass.
02139 was used.
The resole used in each example was dehydrated to below 3% by weight o:E water and bodied at 50-60C for a time sufficien-t to provide the desired viscosity which was measured using a srookfield Viscome-ter Model HsT.
Since viscosity varia-tion with temperature is significant a Brookfield Thermocell was used for the resoles of the examples following hereinafter which comprised a thermo container along with an SCR
controller r Model HT-64, an SC4-27 spindle and an HT-2 sample container. Measurements were made at 25C. All viscosi-ties given were obtained by this technique.
The burst pressure oE the cells oE any particular foam was determined by measuring the closed-cell content of a foam sample, then placing that sample in a pressure tube and applying a small incremental isotropic pressure. After being subjected to that pressure for five minutes the closed-cell content was remeasured.
The sample was then replaced in the tube and pressurized at a slightly higher isotropic pressure Eor five minutes before being measured for closed-cell content again.
This procedure was repeated at even higher pressures and a graph was plotted of closed-cell content against pressure. It was found that, at a characteristic . ~
:
' ' iso-tropic pressure for each foam, the clo.sed-cell content dropped dramatically by at least 10~ and continued to drop thereafter. This pressure is called the "burst pressure".
Density was calculated from an accurately weighed
3.6 cms diameter, and 2.9 cms long core sample.
Having thus generally described the invention, reference will now be made to the following Examples, describing preferred embodiments only.
This Example illustrates the preparation of a phenolic foam slab faced with glass fiber scrim. A
resole having a nominal F/P ratio of 2:1 and containing 2.1~ by weight of water was used to produce a foam according to the invention. All parts are by weight.
The following components were mixed together using a jacketed, continuous mixer, Model 4MHA available from Oakes Machinery Co., 235 Grant Ave., Islip N.Y. 11751.
Resole F/P ratio 2:1 (1) 77.75 parts Viscosity at 25C 95,000 cps Blowinq ~ *Freon 114 (2) 12.1 parts Sur actant DC-193 ~3~ 4 parts F~min~ C~t3~l~g~ (4) 2.05 parts (1) The liquid ~esole contained a dispersed oxalate salt as a result of the neutralization of calcium hydroxide catalyst using oxalic acid.
(2) A fluorocarbon (1,2-dichloro-tetrafluoroethane) available from DuPont under that description.
(3) A silicone based surfactant available from Dow Corning Co. under that description.
~4) A 2:1 weight ratio blend of diethylene glycol and toluene sulfonic acid expressed in terms of acid component content.
The resole, stored at about 5C to minimize *Trade Mark .
~i advancement, was initially brought to room temperature (17C). ~~
The resole and surfactant were initially mixed together at about 3~C in a jacketedJ paddle mixer for about 30 minutes under an absolute pressure of 5 mm. of mercury to avoid entraining air. The resole and surfactant, foaming catalyst and blowing agent were continuously charged to the Oakes mixer in the foregoing noted ratios through rotameter metering devices. The Oakes mixer was operated at about 185 rpm and had tempered water at about 32C flowing through its jacket.
The charge line carrying the resole was traced with hot water at about the same temperature. The blowing agent and catalyst were metered to the mixer at 17C. The temperature of the foam composition entering the mixer was about 32C~ The pressure in the mixer was 5.0 atmospheres. The temperature increase in the high shear mixex should~be minimiæed to limit reaction therein which tends to foul the mixer. Likewise the pressure in the mixer should be above the vapor pressure of the foaming agent to avoid pxemature foaming and with the Freon 114 of this Example, such pressure was kept at about 5.0 atmospheres.
The resulting formulation passed from the mixer through a finite length of insulated txansfer tube consisting of a 91 cms long by 1.27 cms diameter pipe where foaming commenced, to an extrusion head in the form of a 0.48 cm diameter nozæle just upstream of which was a bladder torpedo-control valve ~Tube-O-Matic Valve B-310208 available from Schrider Fluid Power Inc., P.O.
Box 1448-71 Woodland St., ~anchester, Connecticut 06040). This air pressure controlled valve controlled the back pressure in the mixer and delivery tube and the rate of expansion of the oamable mixture issuing from Trade Mark .. ..
'- . ~ - . .
~' -the head. The mass flow rate of the foaming composition through the system was about 440 gms/minute.
The temperature of the mix-ture at the noæzle was 50C while the pressure there was 1 atmosphere; the pressure at the inlet to the control valve was 3.9 atmospheres whereas the tempera-ture at such inlet was 56.7C.
The extrusion head was reciprocated through about 17.7 cms in 1.5 seconds in such a way as to lay down a continuous ribbon of the foaming mi~ture on a sheet of Eiberglass scrim identiEied as Craneglas No. 230, advancing at the rate oE about 76 cms/min.
The distance of the nozzle Erom the moving paper was kep-t at a minimum to minimize entrainment of air~
The mixture was deposited in essentially parallel lines such that as foaming occurred the lines coalesced to Eorm a continuous sheet. The stream issuing from the nozzle has -the consistency of a froth such that rapid expansion without significant entrapment of air occurs as the composition is deposited on the fiber substra-te.
Immediately downstream of the extrusion nozzle a layer oE fiberglass scrim was applied to the upper surface of the rising ~oam sheet. The covered foam sheet was constrained by passage through a heated double belt at 70C, the residence time being 72 seconds, was then passed through a first air oven maintained at 75C, the resiclence time being 4.8 minutes and finally passed to a second air oven where it was maintained at 60C for 118 hours. It was observed -that no seepage of the froth foam through the glass scrim occurred. The scrim adhered to the cured foam sufficiently strongly that it tore when an attempt to pull.it from -the foam was made.
The density of a samp].e of the foam was 2.46 pounds per cu. foot (39~8 kg/m3) and the closed cell content was ' ~ " . ~ .
. "' ' :
~2~
86.2%.
Example 1 was repea-ted with Craneglas 230 glass scrim facings applied -to top and bottom of the foam, except that the foam was allowed -to rise freely. The residence time in the first air oven maintained at 75C, was varied Erom 5 to 30 minutes. Good adhesion to the scrim was obtained. The density and closed cell content is given in Table A.
TABLE A
S~e~ Oven timeDensity Closed Cell (mins) kg.m3 B.l 5 43.9 86.2 B.2 10 41.7 88.6 B.3 15 41.4 86.9 B.4 30 41.7 88.8 The thermal conductivity of the foam was 0~0161 watt/mC.
Example 1 was repeated with Kraft paper substituted for glass scrim facings. The foam was deposited on Kraft paper in a series of sheet metal molds, 5.08 cm high. After the top facing was applied to the rising foam surface, the mold lids were closed to constrain the rising foam. The molds were passed through the first air oven maintained at 80C and residence time in the oven was varied from 4.31 to 60 minutes. The Freon 114 content of the liquid composition prior to frothing and foaming was 11 weight percent. After exiting from the first air oven, the foam slabs were maintained in the second air oven at 60C for 18 hours. Upon cooling of the slabs some shrinkage occurred with slight wrinkling oE the paper. Adhesion of the paper to the foam was moderate since the paper could be stripped from the Eoam.
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0~3 Data Eor density, closed cell conten-t and thermal conduc-tivity are presented in Table B.
TABLE B
Sample Oven tlme Density Closed Cell kl _ (mins) kg.m3 % wat-t/mC
C.l 4.31 52.3 80.0 0.0197 C.2 8.62 40.8 ~0.0 ---C.3 17.24 ~1.8 85.5 ---C.4 25.86 ~1.5 81.7 ---C.5 34.48 45.7 90.3 ---C.6 60 41.0 83.1 0.0162 This example illustrates the preparation of a product similar to Example 3. In this Example, a phenolic foam with a nominal F/P ratio of 2:1 was used.
All parts are by weight.
The Eollowing components were mixed together using a jacketed, continuous mixer, Model 4MHA available from Oakes Machinery Co., 235 Grant Ave., Islip, N.Y. 11751.
Resole F/P ratio 1.93:1 (1) 96 parts Viscosity at 25C 263,000 cps Freon 114 (2) 15 parts SurEac-tant DC-193 (3) 4 parts Foam~ ~ Catalyst (4) 2.2 par-ts (1) to (4) -see notes of Example 1.
The blowing agent was held in a bomb-like container and saturated with air by bubbling air at about 15 atmospheres into i-t for about 4 to 6 hours. This was to promote uniform nucleation of the blowing agent on reduction of the pressures during a subsequent phase of the foaming process.
The resole and surfactan-t were initially mixed together at about 25-40C in a jacke-ted, paddle mixer for about 30 minutes under an absolute pressure of 5mm. of mercury : .. . .
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to avoid en-training air. The resole and surEactant, foaming ca-talyst and blowing agen-t were continuously charged to the Oakes mixer in the foregoing noted ratios through suitable flow metering devices.
Turbine meters ob-tained Erom F'low Technology ~nc., Sacramento, California were used on the Freon and an oval gear meter obtained from Brooks Instrument Division oE Emerson Electric was used on the resole-surfactant acid-catalyst streams. The Oakes mixer was operated at about 93 rpm and had tempered water at about 40C
flowing through its jacket. The charge line carrying the resole was traced with hot water at about the same temperature. The blowing agent and catalyst were metered to the mixer at 25C. The temperatures of the foam composition entering the mixer was about 30-40C
whi]e at the discharge of the mixer it was about 45-50C. The pressure in the mixer was 6.8 atmospheres.
The temperature increase in the high shear mixer should be minimized to limit reaction therein which tends to foul the mixer. Likewise the pressure in the mixer should be abo~e the vapor pressure of the foaming agent to avoid premature Eoaming and with the Freon 114 of this Example, such pressure should be kept at between about 3.4-6.8 atmospheres.
The resul-ting formulation passed from the mixer as described in Example 1 to an extrusion head in the form of a 0.64 cm diameter nozzle just upstream of which was the bladder -torpedo-control valve (see Example 1). The mass ~low rate of the foaming composition through the s~stem was about 430-440 gms/minute.
The temperature of the mixture at the nozzle was 49C while the pressure there was 0.68 atmospheres; the pressure at the inlet to the control valve was 3.9 atmospheres whereas the temperature at such inlet was .
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50.9C.
The extrusion head was reciproca-ted -through about 55.9 cms in 2-~ seconds in such a way as to lay down a continuous rlbbon of -the foaming mixture on a sheet of natural Kraft paper 0.254 mm. thick having a weight of 205 kg/lOOOm2 advancing at the rate oE about 24.4 cms/min.
The distance of the nozzle from the moving paper was kept at a minimum to minimize entrainment of air.
The mixture was deposited in essentially parallel lines such that as foaming occurred the lines coalesced to Eorm a continuous sheetO The stream issuing from the nozzle should have the consistency of a froth such that rapid expansion withou-t significant entrapment of air occurs as -the composition is deposited on the paper substrate.
Immediately downstream of the extrusion nozzle a pro-tective Kraft paper covering was applied to the upper surface of the advancing foam sheet. Such covering (same characteristics as the paper substrate) passed around a fixed roller about 30.5 cms beyond the nozzle into contact with the rising developing foam sheet. The covered foam sheet was then brought into forcible compressive engagement with a succession of six immediately adjacent 3.8 cms diameter freely floating steel rolls interposed across the path of the advancing foam in order to iron out any irregularities in the foam surface and promote good wetting by the foam of the protective upper paper layer. The ,rollers serve to exert a constant pressure on the advancing foam and were vertically positioned so as to come into contact with abou-t the upper 0.64 cms of thickness. This is important since warping of the foam product can occur in the absence of good adhesion with the tip and bottom ~, ,:, .: - .,, -,- - , :.: .
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paper layers brought about by such compressive rolling contact.
The foam sheet covered on its upper and lower faces with -the Kraft paper was then passed through a hot air curing tunnel in the form of an oven obtained from Kornylak Co., 400 ~eaton St., ~lamilton, Ohio, described as a 25 foot Air Film Principle Foam Containment Conveyor. This tunnel oven consisted of a section about 7.6 m long having a succession of five pairs of perforated platens vertically spaced 15.2 cms apart, one of each pair of which was above and below the advancing foam and each of which was about 1.5 m long. A film of hot air controlled at 53C issued from the first pair of platens closest to the extrusion nozzle against the paper-covered upper and lower surfaces of the foam. A
succession of about eight 3.8 cms diameter, immediately adjacent floating rollers were also in the oven under the first platen for contact with the covered upper surface portion of the foam sheet. Air issuing from the remaining platens was kept at temperatures in the range of about 45-55C. The residence time of the foam in such oven was about 31 minutes at which time it had been hardened suf ficiently to be cut with a saw into convenient pieces. These pieces were then stored at 60C for 1~ hours. The above foam product had moderate adhesion of the paper to the foam cure.
Samples of the foam sheet produced by the foregoing process were -tested for density, closed-cell content, burst pressure and thermal conductivity after ten and 100 days. During aging prior to thermal conductivity testing, samples were stored at 73F (23C) and 50%
relative humidity. ~he results set f orth in Table C
following.
.. . .
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Density Burs_ Pressure Closed Cell kl0 kl00_ kg/m3 kg/cm2 % w/mC w/mC
47.4 2.32 97.9 0 D 0165 0.0169 Two Hours Post Cure @ 90C Plus 1 Hr. @ 90C_ Closed Cell klo Density ~ _ % w/mC kg/m3 98.3 0.0167 46.3 Example 4 was repeated with a resole of 82,000 cps viscosi-ty. The same quantities of ingredients were used except that -the Freon 114 content was reduced to 12.9 par-ts. The Oakes mixer was operated at 123 rpm and a jacket temperature of 35C. The temperature of the foam composi-tion entering the mixer was abou-t 36C and exiting was about 45C. The pressure in the mixer was 3.5 atmospheres. The mass flow rate was 35B g/min. The temperature of the froth mixture at -the nozzle was 38C
and the pressure was 0.34 atmospheres.
The extrusion head was reciprocated through about 46 cm~ with a cycle time of 4 seconds to lay down a continuous ribbon of the forth foam on an advancing sheet of fiberglass sole by Johns-Manville under the trademark ~-M Duraglas 7115. The line speed was 0.38 meters per minute. Immediately downstream of the extrusion nozzle, a second layer of fiberglass sheet was applied to the xising foam surface. While the foam passed through the Kornylak oven, constraint was applied to it by means of -the pla-tens as well as the floating rollers. The oven was maintained at 68C. Dwell time . .
- . - .. .
:
. .. .:. ' in the oven was 20 minutes. The Eoam was then stored Eor 18 hours a-t 60C.
The density of the foam was 2.86 pcf (46 ky/m3).
The thermal conductivity (kl) was 0.0157 watts/mC.
Af-ter 100 days a-t 23C it had increased to 0.0173 watts/mC. Good adhesion of the foam to the fiberglass was observed.
Example 5 was repeated in its essential elements, excep-t tha-t the foam was allowed free rise except for the constraint caused by the Eloa-ting rollers positioned ahead oE the Kornylak oven.
The densi-ty of the foam was 3.25 pcE (52.3 kg/m3).
The initial thermal conductivity (kl) was 0.0151 wa-tts/mC and after 100 days at 23C (kloo), i-t was 0.0161 watts/mC. Good adhesion of the foam to the fiberglass was observed.
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Having thus generally described the invention, reference will now be made to the following Examples, describing preferred embodiments only.
This Example illustrates the preparation of a phenolic foam slab faced with glass fiber scrim. A
resole having a nominal F/P ratio of 2:1 and containing 2.1~ by weight of water was used to produce a foam according to the invention. All parts are by weight.
The following components were mixed together using a jacketed, continuous mixer, Model 4MHA available from Oakes Machinery Co., 235 Grant Ave., Islip N.Y. 11751.
Resole F/P ratio 2:1 (1) 77.75 parts Viscosity at 25C 95,000 cps Blowinq ~ *Freon 114 (2) 12.1 parts Sur actant DC-193 ~3~ 4 parts F~min~ C~t3~l~g~ (4) 2.05 parts (1) The liquid ~esole contained a dispersed oxalate salt as a result of the neutralization of calcium hydroxide catalyst using oxalic acid.
(2) A fluorocarbon (1,2-dichloro-tetrafluoroethane) available from DuPont under that description.
(3) A silicone based surfactant available from Dow Corning Co. under that description.
~4) A 2:1 weight ratio blend of diethylene glycol and toluene sulfonic acid expressed in terms of acid component content.
The resole, stored at about 5C to minimize *Trade Mark .
~i advancement, was initially brought to room temperature (17C). ~~
The resole and surfactant were initially mixed together at about 3~C in a jacketedJ paddle mixer for about 30 minutes under an absolute pressure of 5 mm. of mercury to avoid entraining air. The resole and surfactant, foaming catalyst and blowing agent were continuously charged to the Oakes mixer in the foregoing noted ratios through rotameter metering devices. The Oakes mixer was operated at about 185 rpm and had tempered water at about 32C flowing through its jacket.
The charge line carrying the resole was traced with hot water at about the same temperature. The blowing agent and catalyst were metered to the mixer at 17C. The temperature of the foam composition entering the mixer was about 32C~ The pressure in the mixer was 5.0 atmospheres. The temperature increase in the high shear mixex should~be minimiæed to limit reaction therein which tends to foul the mixer. Likewise the pressure in the mixer should be above the vapor pressure of the foaming agent to avoid pxemature foaming and with the Freon 114 of this Example, such pressure was kept at about 5.0 atmospheres.
The resulting formulation passed from the mixer through a finite length of insulated txansfer tube consisting of a 91 cms long by 1.27 cms diameter pipe where foaming commenced, to an extrusion head in the form of a 0.48 cm diameter nozæle just upstream of which was a bladder torpedo-control valve ~Tube-O-Matic Valve B-310208 available from Schrider Fluid Power Inc., P.O.
Box 1448-71 Woodland St., ~anchester, Connecticut 06040). This air pressure controlled valve controlled the back pressure in the mixer and delivery tube and the rate of expansion of the oamable mixture issuing from Trade Mark .. ..
'- . ~ - . .
~' -the head. The mass flow rate of the foaming composition through the system was about 440 gms/minute.
The temperature of the mix-ture at the noæzle was 50C while the pressure there was 1 atmosphere; the pressure at the inlet to the control valve was 3.9 atmospheres whereas the tempera-ture at such inlet was 56.7C.
The extrusion head was reciprocated through about 17.7 cms in 1.5 seconds in such a way as to lay down a continuous ribbon of the foaming mi~ture on a sheet of Eiberglass scrim identiEied as Craneglas No. 230, advancing at the rate oE about 76 cms/min.
The distance of the nozzle Erom the moving paper was kep-t at a minimum to minimize entrainment of air~
The mixture was deposited in essentially parallel lines such that as foaming occurred the lines coalesced to Eorm a continuous sheet. The stream issuing from the nozzle has -the consistency of a froth such that rapid expansion without significant entrapment of air occurs as the composition is deposited on the fiber substra-te.
Immediately downstream of the extrusion nozzle a layer oE fiberglass scrim was applied to the upper surface of the rising ~oam sheet. The covered foam sheet was constrained by passage through a heated double belt at 70C, the residence time being 72 seconds, was then passed through a first air oven maintained at 75C, the resiclence time being 4.8 minutes and finally passed to a second air oven where it was maintained at 60C for 118 hours. It was observed -that no seepage of the froth foam through the glass scrim occurred. The scrim adhered to the cured foam sufficiently strongly that it tore when an attempt to pull.it from -the foam was made.
The density of a samp].e of the foam was 2.46 pounds per cu. foot (39~8 kg/m3) and the closed cell content was ' ~ " . ~ .
. "' ' :
~2~
86.2%.
Example 1 was repea-ted with Craneglas 230 glass scrim facings applied -to top and bottom of the foam, except that the foam was allowed -to rise freely. The residence time in the first air oven maintained at 75C, was varied Erom 5 to 30 minutes. Good adhesion to the scrim was obtained. The density and closed cell content is given in Table A.
TABLE A
S~e~ Oven timeDensity Closed Cell (mins) kg.m3 B.l 5 43.9 86.2 B.2 10 41.7 88.6 B.3 15 41.4 86.9 B.4 30 41.7 88.8 The thermal conductivity of the foam was 0~0161 watt/mC.
Example 1 was repeated with Kraft paper substituted for glass scrim facings. The foam was deposited on Kraft paper in a series of sheet metal molds, 5.08 cm high. After the top facing was applied to the rising foam surface, the mold lids were closed to constrain the rising foam. The molds were passed through the first air oven maintained at 80C and residence time in the oven was varied from 4.31 to 60 minutes. The Freon 114 content of the liquid composition prior to frothing and foaming was 11 weight percent. After exiting from the first air oven, the foam slabs were maintained in the second air oven at 60C for 18 hours. Upon cooling of the slabs some shrinkage occurred with slight wrinkling oE the paper. Adhesion of the paper to the foam was moderate since the paper could be stripped from the Eoam.
, : : :
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0~3 Data Eor density, closed cell conten-t and thermal conduc-tivity are presented in Table B.
TABLE B
Sample Oven tlme Density Closed Cell kl _ (mins) kg.m3 % wat-t/mC
C.l 4.31 52.3 80.0 0.0197 C.2 8.62 40.8 ~0.0 ---C.3 17.24 ~1.8 85.5 ---C.4 25.86 ~1.5 81.7 ---C.5 34.48 45.7 90.3 ---C.6 60 41.0 83.1 0.0162 This example illustrates the preparation of a product similar to Example 3. In this Example, a phenolic foam with a nominal F/P ratio of 2:1 was used.
All parts are by weight.
The Eollowing components were mixed together using a jacketed, continuous mixer, Model 4MHA available from Oakes Machinery Co., 235 Grant Ave., Islip, N.Y. 11751.
Resole F/P ratio 1.93:1 (1) 96 parts Viscosity at 25C 263,000 cps Freon 114 (2) 15 parts SurEac-tant DC-193 (3) 4 parts Foam~ ~ Catalyst (4) 2.2 par-ts (1) to (4) -see notes of Example 1.
The blowing agent was held in a bomb-like container and saturated with air by bubbling air at about 15 atmospheres into i-t for about 4 to 6 hours. This was to promote uniform nucleation of the blowing agent on reduction of the pressures during a subsequent phase of the foaming process.
The resole and surfactan-t were initially mixed together at about 25-40C in a jacke-ted, paddle mixer for about 30 minutes under an absolute pressure of 5mm. of mercury : .. . .
.. .
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.:
to avoid en-training air. The resole and surEactant, foaming ca-talyst and blowing agen-t were continuously charged to the Oakes mixer in the foregoing noted ratios through suitable flow metering devices.
Turbine meters ob-tained Erom F'low Technology ~nc., Sacramento, California were used on the Freon and an oval gear meter obtained from Brooks Instrument Division oE Emerson Electric was used on the resole-surfactant acid-catalyst streams. The Oakes mixer was operated at about 93 rpm and had tempered water at about 40C
flowing through its jacket. The charge line carrying the resole was traced with hot water at about the same temperature. The blowing agent and catalyst were metered to the mixer at 25C. The temperatures of the foam composition entering the mixer was about 30-40C
whi]e at the discharge of the mixer it was about 45-50C. The pressure in the mixer was 6.8 atmospheres.
The temperature increase in the high shear mixer should be minimized to limit reaction therein which tends to foul the mixer. Likewise the pressure in the mixer should be abo~e the vapor pressure of the foaming agent to avoid premature Eoaming and with the Freon 114 of this Example, such pressure should be kept at between about 3.4-6.8 atmospheres.
The resul-ting formulation passed from the mixer as described in Example 1 to an extrusion head in the form of a 0.64 cm diameter nozzle just upstream of which was the bladder -torpedo-control valve (see Example 1). The mass ~low rate of the foaming composition through the s~stem was about 430-440 gms/minute.
The temperature of the mixture at the nozzle was 49C while the pressure there was 0.68 atmospheres; the pressure at the inlet to the control valve was 3.9 atmospheres whereas the temperature at such inlet was .
.. .: : : :
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50.9C.
The extrusion head was reciproca-ted -through about 55.9 cms in 2-~ seconds in such a way as to lay down a continuous rlbbon of -the foaming mixture on a sheet of natural Kraft paper 0.254 mm. thick having a weight of 205 kg/lOOOm2 advancing at the rate oE about 24.4 cms/min.
The distance of the nozzle from the moving paper was kept at a minimum to minimize entrainment of air.
The mixture was deposited in essentially parallel lines such that as foaming occurred the lines coalesced to Eorm a continuous sheetO The stream issuing from the nozzle should have the consistency of a froth such that rapid expansion withou-t significant entrapment of air occurs as -the composition is deposited on the paper substrate.
Immediately downstream of the extrusion nozzle a pro-tective Kraft paper covering was applied to the upper surface of the advancing foam sheet. Such covering (same characteristics as the paper substrate) passed around a fixed roller about 30.5 cms beyond the nozzle into contact with the rising developing foam sheet. The covered foam sheet was then brought into forcible compressive engagement with a succession of six immediately adjacent 3.8 cms diameter freely floating steel rolls interposed across the path of the advancing foam in order to iron out any irregularities in the foam surface and promote good wetting by the foam of the protective upper paper layer. The ,rollers serve to exert a constant pressure on the advancing foam and were vertically positioned so as to come into contact with abou-t the upper 0.64 cms of thickness. This is important since warping of the foam product can occur in the absence of good adhesion with the tip and bottom ~, ,:, .: - .,, -,- - , :.: .
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paper layers brought about by such compressive rolling contact.
The foam sheet covered on its upper and lower faces with -the Kraft paper was then passed through a hot air curing tunnel in the form of an oven obtained from Kornylak Co., 400 ~eaton St., ~lamilton, Ohio, described as a 25 foot Air Film Principle Foam Containment Conveyor. This tunnel oven consisted of a section about 7.6 m long having a succession of five pairs of perforated platens vertically spaced 15.2 cms apart, one of each pair of which was above and below the advancing foam and each of which was about 1.5 m long. A film of hot air controlled at 53C issued from the first pair of platens closest to the extrusion nozzle against the paper-covered upper and lower surfaces of the foam. A
succession of about eight 3.8 cms diameter, immediately adjacent floating rollers were also in the oven under the first platen for contact with the covered upper surface portion of the foam sheet. Air issuing from the remaining platens was kept at temperatures in the range of about 45-55C. The residence time of the foam in such oven was about 31 minutes at which time it had been hardened suf ficiently to be cut with a saw into convenient pieces. These pieces were then stored at 60C for 1~ hours. The above foam product had moderate adhesion of the paper to the foam cure.
Samples of the foam sheet produced by the foregoing process were -tested for density, closed-cell content, burst pressure and thermal conductivity after ten and 100 days. During aging prior to thermal conductivity testing, samples were stored at 73F (23C) and 50%
relative humidity. ~he results set f orth in Table C
following.
.. . .
' ' ~ .
": ' ' T~BLE C
Density Burs_ Pressure Closed Cell kl0 kl00_ kg/m3 kg/cm2 % w/mC w/mC
47.4 2.32 97.9 0 D 0165 0.0169 Two Hours Post Cure @ 90C Plus 1 Hr. @ 90C_ Closed Cell klo Density ~ _ % w/mC kg/m3 98.3 0.0167 46.3 Example 4 was repeated with a resole of 82,000 cps viscosi-ty. The same quantities of ingredients were used except that -the Freon 114 content was reduced to 12.9 par-ts. The Oakes mixer was operated at 123 rpm and a jacket temperature of 35C. The temperature of the foam composi-tion entering the mixer was abou-t 36C and exiting was about 45C. The pressure in the mixer was 3.5 atmospheres. The mass flow rate was 35B g/min. The temperature of the froth mixture at -the nozzle was 38C
and the pressure was 0.34 atmospheres.
The extrusion head was reciprocated through about 46 cm~ with a cycle time of 4 seconds to lay down a continuous ribbon of the forth foam on an advancing sheet of fiberglass sole by Johns-Manville under the trademark ~-M Duraglas 7115. The line speed was 0.38 meters per minute. Immediately downstream of the extrusion nozzle, a second layer of fiberglass sheet was applied to the xising foam surface. While the foam passed through the Kornylak oven, constraint was applied to it by means of -the pla-tens as well as the floating rollers. The oven was maintained at 68C. Dwell time . .
- . - .. .
:
. .. .:. ' in the oven was 20 minutes. The Eoam was then stored Eor 18 hours a-t 60C.
The density of the foam was 2.86 pcf (46 ky/m3).
The thermal conductivity (kl) was 0.0157 watts/mC.
Af-ter 100 days a-t 23C it had increased to 0.0173 watts/mC. Good adhesion of the foam to the fiberglass was observed.
Example 5 was repeated in its essential elements, excep-t tha-t the foam was allowed free rise except for the constraint caused by the Eloa-ting rollers positioned ahead oE the Kornylak oven.
The densi-ty of the foam was 3.25 pcE (52.3 kg/m3).
The initial thermal conductivity (kl) was 0.0151 wa-tts/mC and after 100 days at 23C (kloo), i-t was 0.0161 watts/mC. Good adhesion of the foam to the fiberglass was observed.
', '' : : ~ ~ '`
Claims (8)
1. A method of forming an insulation board or the like, in which various types of substrates, of a fibrous nature, can be integrally bonded to the foam by first of all initially pre-foaming a foamable polymer, namely a phenolic polymer, bringing a substrate surface and the foam into contact or juxtaposition with each other, permitting the pre-foamed polymer to foam further, and subsequently curing the resulting foam product.
2. A method for continuously producing an insulation board comprising a rigid plastic foam core having two major surfaces and a facing material on at least one of the major surfaces, the method comprising:
(a) conveying a facing material along a production line, (b) depositing a partially expanded froth foam, which contains at least one blowing agent, on the facing material, the partially expanded froth foam comprising a mixture for forming a rigid polymer foam selected from the group consisting of phenolic polymer foam, and the blowing agent being easily vaporizable at atmospheric pressure, and (c) further expanding and curing the froth foam in contact with the facing material to form the insulation board.
(a) conveying a facing material along a production line, (b) depositing a partially expanded froth foam, which contains at least one blowing agent, on the facing material, the partially expanded froth foam comprising a mixture for forming a rigid polymer foam selected from the group consisting of phenolic polymer foam, and the blowing agent being easily vaporizable at atmospheric pressure, and (c) further expanding and curing the froth foam in contact with the facing material to form the insulation board.
3. The method of Claim 1 for continuously producing an insulation board having fibrous layers on both major surfaces of a foam core comprising:
(a) conveying at least one lower fibrous layer along a production line, (b) depositing the partially expanded froth foam on the lower fibrous layer, (c) placing at least one advancing upper fibrous layer on the deposited, partially expanded froth foam to form an advancing sandwich of upper and lower fibrous layers and intermediate froth foam, and (d) further expanding and curing the froth foam in contact with the fibrous layers to form a rigid plastic foam core covered on both major surfaces with and penetrating interstices of the fibrous layers.
(a) conveying at least one lower fibrous layer along a production line, (b) depositing the partially expanded froth foam on the lower fibrous layer, (c) placing at least one advancing upper fibrous layer on the deposited, partially expanded froth foam to form an advancing sandwich of upper and lower fibrous layers and intermediate froth foam, and (d) further expanding and curing the froth foam in contact with the fibrous layers to form a rigid plastic foam core covered on both major surfaces with and penetrating interstices of the fibrous layers.
4. The method of Claim 2 for continuously producing an insulation board having fibrous layers on both major surfaces of foam core comprising:
(a) conveying at least one lower fibrous layer along a production line, (b) depositing the partially expanded froth foam on the lower fibrous layer, (c) placing at least one advancing upper fibrous layer on the deposited, partially expanded froth foam to form an advancing sandwich of upper and lower fibrous layers and intermediate froth foam, and (d) passing the sandwich through the nip of rotating rolls to meter the amount of froth foam and help it to penetrate the interstices of the fibrous layers, and (e) thereafter passing the sandwich from the nip of the rotating rolls into a heated expansion zone, whereby the froth foam further expands and cures in contact with the fibrous layers to form a rigid plastic foam core covered on both major surfaces with and penetrating interstices of the fibrous layers.
(a) conveying at least one lower fibrous layer along a production line, (b) depositing the partially expanded froth foam on the lower fibrous layer, (c) placing at least one advancing upper fibrous layer on the deposited, partially expanded froth foam to form an advancing sandwich of upper and lower fibrous layers and intermediate froth foam, and (d) passing the sandwich through the nip of rotating rolls to meter the amount of froth foam and help it to penetrate the interstices of the fibrous layers, and (e) thereafter passing the sandwich from the nip of the rotating rolls into a heated expansion zone, whereby the froth foam further expands and cures in contact with the fibrous layers to form a rigid plastic foam core covered on both major surfaces with and penetrating interstices of the fibrous layers.
5. An insulation board or the like which has a core or layer of plastic foam of a phenolic resin with a substrate layer in juxtaposition with the surface of the foam, the substrate layer having fibrous material associated therewith so that the fibrous material of the substrate layer and the foam are firmly bonded or attached together by virtue of the foam having been at least partially expanded while in contact with the substrate layer so that fibers of the substrate layer are embedded in or secured by the foam.
6. An insulation board comprising a core of rigid plastic foam having two major, substantially parallel surfaces and a facing material on at least one of the major surfaces of the core, the foam core being formed in accordance with the method of Claim 1 by further expanding a partially expanded froth foam in contact with the facing material, and the cells of the resulting
7. The method of any of Claims 1, 3 and 4, wherein the fibrous layer is cardboard, a paper product, an asbestos composite or a glass fiber sheet.
8. The insulation board of any of Claims 5 and 6 wherein the fibrous material is cardboard, a paper product, an asbestos composite or a glass fiber sheet.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA539376A CA1268608C (en) | 1987-06-10 | 1987-06-10 | Phenolic foam products and method of production |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA539376A CA1268608C (en) | 1987-06-10 | 1987-06-10 | Phenolic foam products and method of production |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA1268608A true CA1268608A (en) | 1990-05-08 |
| CA1268608C CA1268608C (en) | 1990-05-08 |
Family
ID=4135864
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA539376A Expired - Lifetime CA1268608C (en) | 1987-06-10 | 1987-06-10 | Phenolic foam products and method of production |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1268608C (en) |
-
1987
- 1987-06-10 CA CA539376A patent/CA1268608C/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| CA1268608C (en) | 1990-05-08 |
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