CA1265895A

CA1265895A - Method of making plastics cellular material

Info

Publication number: CA1265895A
Application number: CA000491999A
Authority: CA
Inventors: Craig Drennan; Jerry P. Shira
Original assignee: Phoenix Foam Inc
Current assignee: Phoenix Foam Inc
Priority date: 1985-10-01
Filing date: 1985-10-01
Publication date: 1990-02-13
Anticipated expiration: 2007-02-13

Abstract

ABSTRACT

This invention relates to a process for production of a plastics cellular material. The process comprises mixing a first mixture of a fast-curing resin that may be cured with an organic peroxide catalyst, a co-polymerizeable monomer, finely dispersed surfactants, finely dispersed gas releasing salt, hardening accelerators. The fast-curing resin and the co-polymerizeable monomer together in combination have a viscosity level in the range of 1875 CPS and 2725 CPS at 25°C. An acidic solution and organic peroxide catalysts are then mixed into the first mixture to form a second mixture that will foam in a controllable manner and cure to produce a foam material of desired density.

Description

~23~ 5 .~
This invention relates to a method of making a plastics cellular material This invention provides a method oE making plastics cellular materials of varying densities from 2 to 35 lbs per cubic foot for applications whicll require a foarn of substantial strength.
At the mid-range and lower densities, this plastic cellular material has particular application for use in sandwich boards, building materialsl furniture, automobile bodies, home renovations, room additions to residential houses, filler for trailor and truck bodies, marine and floatation products, and filler for airplane bodies. These applications use a composite system, i.e. a sandwich of foam covered with a skin on each side.
other analogous uses will be apparent.
Regarding the higher densities of greater than 25 lb/ft3, the plastics cellular material of this invention has particular application as a substitute for balsa wood or ply wood. At these higher densities, a plastics cellular material is provided that has a tensile strength adequate to functionally replace balsa wood or ply wood. These applications also use a composite system, i.e.
a sandwich of foam covered with a skin on each side Urethane cellular material has been and is being used for a number of these applications. urethane cellular material has not been satisfactory because its cellular structure tends to break down from the expansion, contraction or general stress that occurs in use. uretllane cellular material has a tendency to over-contract and over-expand during use.

. ~

Other available foams have also been found to be inadequate because there was no known process for making them with the properties required for the noted applications.
A general plastics cellular material having a polyester resin, an epoxy-based vinyl ester and fillers is taught in U.S.
patent 4,482,649 granted to Jerry Shira and Alex l~iutel. Before the invention disclosed herein, one was able to achieve the equivalent densities required for the noted applications but there was no known process to also provide this foam with the necessary tensile strength required in combination with those densities.
The required strength could be achieved but the weight of the plastics cellular material then became too heavy.
A further obstacle to providing a process for a foam with the desired properties is that foams with a relatively high proportion of fillers have not been useful for the applications noted in this disclosure because they are too heavy for the amount of strength that they impart. It has generally been thought in the art that these fillers had to be kept in the foam because they achieved an essential nucleation function in the foam's structure.
An object of this invention is to provide a process for making a plastics cellular material that is relatively light and strong.
Another object of this invention is to provide a process for making a plastics cellular material that has a high resistance to compression, ~ ~ 2 -~26~

According to this invention, a process for production of a plastics cellular material comprises mixing a first rnixture of a fast-curing resin that may be cured with an organic peroxide catalyst, a co-polymerizeable monomer, finely dispersed surfactants, finely dispersed gas releas.ing salt, hardening accelerators wherein said fast-curing resin and said co-polymerizeable monomer together in combination have a viScosity level in the range of 1875 CPS and 2725 CPS at 25C; mixing into the said first mixture an acidic solution for reaction with the gas releasing salt as a blowing agent, and organic peroxide catalysts to form a second mixture that will foam in a controllable manner and - 2a -2667dl-JM3 cure to produce a foam material of desired density.
The acidic solution and the organic peroxide catalyst may be mixed together to form a separate second mixture before being added to the first mixture which includes the resin, the co-polymerizeable monomer, the gas releasing salt, the hardening accelerators, and the dispersed surfactants. The two mixtures may then be mixed to form a third mixture that will foam in a controllable manner and cur~ to produce a foam material of desired density.
It is also within the scope of this invention to simultaneously mix into the first mixture a second solution having an acid and a third solution having a peroxide catalyst to form a fourth solution that will foam and cure in a controllable manner.
In this case, the acid solution and the organic peroxide catalyst are not pre-mixed together before being added to the first mixture which includes the resin and the co-polymerizeable monomer. By not pre-mixing the acid and the catalyst in the same solution, the overall resulting foaming mixture will foam more rapidly and to a greater extent than if the acid and the catalyst were premixed together. The reason for this increasing foaming behaviour is if the catalyst and acid are premixed, the catalyst will tend to absorb and incapacitate a portion of the acid to prevent it from reacting with the gas-releasing salt to provide blowing for the foam. It is therefore easier to achieve lower densities of the resulting plastics material by not pre-mixing the acid and the peroxide catalyst together before being added to the first mixture. Another aspect of not pre-mixing the acid and the ~6~

2667dl-JM3 catalyst, is that a lesser amount of acid is required to achieve a foam of equitable density.
This invention will be more clearly understood after reference to the ollowing detailed specification.
For descriptive purposes, the process for the production of a foam material wherein two mixtures are first be prepared and then brought together to react with each other and cause foaming will now be described in more detail.
The first mixture customarily includes an unsaturated fast-curing resin, a vinyl co-polymerizeable monomer compound, a finely dispersed gas releasing salt, hardening accelerators and finely dispersed surfactant. The fast-curing resin is curable with an organic peroxide catalyst.
This invention achieves its result by using a higher viscosity resin-co-polymerizeable monomer mix. This viscosity is measured exclusive of the other components in the overall first mix. The higher viscosity of the resin mix is achieved by controlling the amount of copolymerizeable monomer mixed with the resin. The greater the amount of monomer mixed in, the lower the ~iscosity of the resulting resin-monomer mix will be. However, to achieve the applications of this invention, the viscosity of the

2~67dl-JM3 resin-monomer mix must be above the 1875 CPS level and below the 27~5 CPS level (measured at 25C). Once the proper range of viscosity has been achieved for the resin-monomer mix, fillers may ~urther be added to achieve the desired density.
The resin-monomer mix preferably used includes an epoxy-based vinyl ester as its fast-curing resin component. Other resins may be used providing that a minimum viscosity level of greater than 1875 CPS is attained for the resin-monomer mix. It is also required that the fast-curing resin used be curable with an organic peroxide catalyst. Epoxy-based vinyl esters of a dilution not greater than 40 per cent co-polymerizeable monomer are preferable because they have a higher viscosity level than if the monomer content was higher. This high viscosity causes the final foam product to maintain a tighter cell structure then would be achieved with a more diluted resin, i.e. monomer content greater than ~0%. Generally speaking the higher the viscosity, the more resilient the resulting foam will be. In contrast, the more monomer and the more lower the viscosity, the more brittle the result;ng foam will be. Brittleness is not a desired feature ~or the product.
Epoxy-based vinyl esters are already sold in diluted form having cross-linking co-polymerizeable monomers such as styrene.
Monomers, in general, are added by the manufacturer to the epoxy-based vinyl ester mix to impart cross-linking properties to the mixture. As well as styrene, some manufacturers also mix in the acrylic monomer methyl metacrylate. In some of these commercially available mixes, it is quite common for an epoxy-based vinyl ester to be diluted with up to 45% or 50%

2667dl-JM3 styrene by weight. Because monomers such as styrene reduce the viscosity of these epoxy-based vinyl ester mixes, these mixes usually have a low viscosity (i.e. approximately in the range from 350 to 1000 C~S at 25C). This is an unacceptable viscosity level to achieve the objectives of a sufficient strength:density ratio for a foam required for the applications noted in the disclosure. A large portion of the monomer and/or filler must be removed in order to obtain the desired viscosity. The monomer content should not be greater than 40~ of the mix. If the content is greater than 40%, the vlscosity of the resulting foam will be too low. The resulting foam will be prone to breakdown that can come as the result of expansion and contraction that occurs in general use. For example, foam used in a sandwich board must be able to undergo the stress associated with the expansion and contraction that occurs in many applications.
Generally speaking, the structure of epoxy-based vinyl ester may be represented by the following configuration:
V-E-EC-E-V
where the letter V represents a vinyl group, E represents an ester group and EC represents a epoxy component.
The following is an example of a configuration for a possible epoxy-based vinyl èster:
O r OH C OH O
c=c-c-otc-c-o ~C~30 ,c-c-c-o-c-c=c The reactive sites are located at the double bonds at the ends of the two vinyl-ended molecule.

lZ6~395 2667dl-JM3 Some epoxy-based vinyl ester and co-polymerizeable monomer mixes which may be used successfully and are commercially available are sold under the following labels: i) DERAKANE -510N (a trade mark of Dow Chemical Canada Inc.), ii) DERAKANE -510A (a trade mark of Dow Chemical Canada Inc.), iii) DERAKANE
411-30, iv) DERA~.ANE 411-35, v) DERAKANE 411-40, iii) DERAKANE -XD80804 (a trade mark of Dow Chemical Canada Inc.), and iv) HETRON 922 ~a trade mark of Ashland Chemicals). Further to having an epoxy-based vinyl ester and a co-polymerizeable polymer, some of these mixes are further diluted with fillers.
The difference generally in the above-mentioned resin mixe~ is in their additives or fillers and the qualities that those additives or fillers impart.
Fillers may be added to the foam material to reduce its cost of manufacture or to impart a degree of fire retardancy.
However, as aforementioned, fillers generally add weight to the foam. Even though they increase the overall viscosity of the foaming mix, the addition of fillers is generally detrimental to the strength:density ratio of the foam.
The number and types of fillers that may be added to a foam mixture are many. For example! three fillers that may be added are hydrated aluminum oxide, leadless borax glass and zinc borate.
Hydrated aluminum oxide can be used as an effective fire retardant filler. When a foam is exposed to heat, water molecules will separate out from the aluminum oxide at between temperatures of 220C and 600C. The aluminum oxide which is leEt over after the water loss, has excellent heat resistance and a melting point ~z~

2667dl-JM3 above 1600C.
Leadless borax glass filler has a low melting point of approximately 700 to 750C. When it melts it forms a spreaded li~uidous layer that seals cracks, pores and like areas of exposure of the resin binding.
Zinc borate has a melting point of approximately 500C.
~hen heat is applied, this filler will temporarily remain in a m~lted state and spread over the heated surface of the resin binder to cover it with a thin homogeneous layer. As with the case of leadless borax-type powdered glass, this liquidity acts as a physical barrier to protect the resin binder from oxidation under conditions of high temperature encountered in fire.
There are many other fillers that may be used depending upon the desired result. Those skilled in the art will appreciate which fillers to add to suit a specific purpose.
Those skilled in the art will know which commercially available resin-co-polymerizable monomer mix along with the concentration of filler added thereto or to be added thereto in order to achieve a specific result. For instance, DERAKANE - 510A
(a trade mark of Dow Chemical Canada Inc.) has rubber fillers. If it was desired that the foam should have a cushioning quality and i less strength was required for the application, then a person might consider the use of this particular epoxy-based vinyl ester and monomer mix having rubber additives. Although, this filler would incerase the viscosity of the Eirst mixture in~o which the resin mix is being added, the filler would not be desired in excessive quantities because it would add too much weight to the foam for the amount of strength that it would impart.

_ ~ _ 2667dl-JM3 It will be apparent that the high viscosity level for the resin-monomer mix cause that the first mixture into which it is added to have the physical characteristic of being more gelintanous than it would be i~ the viscosity was lower. Under some circumstances in making this foam, problems may arise because the first mixture is too thick to be properly mixed in with the said second mixture. It will be explained later on in this disclosure how this problem may be overcome.
The next item in the first mixture, in the general ormulation, is the finely dispersed gas-releasing salt, usually a carbonate or bicarbonate.
This is introduced for blowing purposes to react with the acid of the second mixture. The bicarbonate must be reactable with the acid and also have safe toxicity. In this particular embodiment, sodium bicarbonate also performs the function of a nucleation filler.
The next item in the first mixture, in the general formulation, is the hardening accelerators.
As those skilled in the art are aware, accelerators are required to break down the organic peroxides, which are the catalysts, to form free radicals to initiate the cross-linking process, i.e. the cross-linking of the unsaturated polymers, the epoxy vinyl esters and the monomers. In effect, the accelerators solve tha problem of adding heat to the system in order to initiate the catalyzation process. There are basically two types of accelerators commonly used: they are either a tertiary amine type or an organo metallic salt type. Three accelerators that have been found to be satisfactory are dimethyl anilene, dimethyl _ g ~z~

2667dl-JM3 paratoluidene, and cobalt octoate.
The next item in the first mixture, of the general formulation, is the surfactants.
Surfactants are asymetrical molecules which reduce the surface tension of the mixture by making the lipophyllic and hydrophyllic components compatible. Surfactants allow for improved distribution of the blowing agent ~hroughout the mixture and they also prevent the foam from collapsing.
Manufacturers of surfactants publish technical information about their products and, in selecting a surfactant, one examines manufacturers' specifications with a view to finding a surfaetant that is effective for the particular components in the mixtures where the surfaetant is reguired. For example. The 3M Company distribute surfactants under their trade mark FLUORAD, and under this brand they have a surfactant identified as FC-430 that is speeified to have exeellent effectiveness with epoxy systems and with polyester systems. This surfactant is especially useful.
Dow Corning Corporation publish information about silieon surfaetants and their DOW CORNING 197 (a trade mark of Dow Corning Corporation) surfaetant of the nonionic silicon glycol copolymer type has also been found to have extraordinary effectiveness with this invention. DOW CORNING 198 (a trade mark of Dow Corning Corporation) may also be used.
The surfactant identified herein as DOW CORNING 197 (a trade mark of Dow Corning Corporation) has been used satisfaetorily with this invention in amounts from 0.3 to 1.0 w.p.
(to 100 w.p. of unfilled polymers and monomers).

2667dl-JM3 It is contemplated that other surfactants eapable of reducing the surface tension in a mixture to provide for improved distribution of blowing may be substituted for those identified herein.
As mentioned above, the second mixture which is seperately mixed and, in this process, added to the first mixture ean, in the broadest aspeet of the invention be a mixture o~ the type previously used in the production of foam materials according to the prior art.
The seeond mixture eustomarily includes an acidie solution which will react with the gas-releasing salt as blowing agent, and organic catalysts.
There are many acceptable acidie solutions.
The acidic solution should be adjusted to compliment the resinous eomposition. When the pH of the acid is modified, the surfaetaney and fire-retardancy of the final product can be modified through the introduction of the inorganic salt solution.
The following aqueous solution has been successfully used, in this invention, in the following ranges of proportions:
water - 5.0 to 10.0 w.p. (per 100 w.p. unfilled polymers and monomers) citric acid - 1.0 to 7.0 w.p. (per 100 w.p. unfilled polymers and monomers) aeetic aeid - 0.5 to 3.0 ~.p. (per 100 w.p. unfilled polymers and monomers) As aforementioned, the eontrast in the viscosity between 2667dl-JM3 that of the first said mixture and that of the said second mixture may be too great to be overcome by the mixer of a conventional delivery system used to mix foaming material. The cause of this problem may be that the mixer on a conventional delivery system is not of a quality to properly stir the low ~iscosity first mixture in with the higher viscosity second mixture. There is difficulty in using a stick pump to pump low viscosity liquids. ThiS problem may be overcome by changing the form of pump used or by adding a quantity of a form of gel to the acid mixture. The addition of a compatible gel will raise the viscosity of the second solution.
For example, fumed silica gel may be added. By adding the silica gel to the acid mixture, the said second mixture becomes more gel-like and more viscous. By imparting these characteristics to the second mixture, the resulting foam more readily is mixed and cured. Gels other than silica gel, that may be used, will be apparent.
Two brands of silica gel that have been used effectively are MICROSIL GP (a trade mark of J. Crosfield & Sons) manufactured by J. Crosfield & Sons and SYLOD255 (a trade mark of Davidson Chemical) manufactured by Davidson Chemical.
In summary, the addition of the fumed silica gel to the acid solution adds structural strength to the foam, facilitates the mixing of the ingredients by the foam delivery system makes the two solutions being mixed more compatible with each other by bridging their physical characteristics.
To the above noted acid solution, fumed silica gel may be added in proportions of between .5 w.p. and 4.5 w.p. (per 100 w.p.
unfilled polymers and monomers) ~5~35 2667dl-JM3 Generally, the more diluted the acidic solution is, the greater the quantity of the solution will be required to be added to the mix. Excessive amounts of water are not desireable. The following ratio has been found not to produce acetic acid odor and introduce an acceptable amount of water:
water - 10.0 w.p. (per 100 w.p.
unfilled polymers and monomers) citric acid - 4.0 w.p. (per 100 w.p.
unfilled polymers and monomers) acetic acid - 1.0 w.p. (per 100 w.p.
unfilled polymers and monomers) Triethyl phosphate with or without citric-acidic acid can also been used. It has been found that triethyl phosphate allows for a more controlled distribution of the ingredients by slowing the speed at which the gaseous bubbles are released during the blowing process.
The next item in the second mixture, of the general for~ula, is the organic catalyst. Catalysts are required to cure the resins and the copolymerizeable monomers; they accomplish this a~ter being activated by accelerators.
In this invention, benzoyl peroxide can be used as the main catalyst; it is very reactive in ambient temperatures.
Benzoyl peroxide has been effectively used in amounts form 4.5 to 6.5 w.p. tper 100 w.p. unfilled polymers and monomers).
The following are examples of quantities and ingredients 9~
2667dl-JM3 that may be used to produce foams of particular densities. They are examples only and it is not meant th~t they be interpreted as bein~ all-inclusive of all the possible foams that may be produced according to this invention.
E.YAMPLE ONE

First mixture:
Epoxy-based vinyl ester and monomer mix*100.00 wp FC - 430 .70 wp DC - 197 .80 wp Dimethyl Anilene .13 wp Dimethyl Paratoluidene.30 wp Cobalt Napthanate .15 wp Sodium Bicarbonate12.00 wp Second mixture:
Acid Solution** 3.00 wp Benzoyl Peroxide 5.50 wp * Some vinyl esters that may be used are DERAKANE - 510N ~trade mark of Dow Chemical Canada Inc.), DERAKANE -510A ~trade mark of Dow Chemical Canada Inc.), DERAKANE -XD80804 ~trade mark of Dow Chemical Canada Inc.), DERAKANE -411 ~trade mark of Dow Chemical Canada Inc.),HETRON 922 ~trade mark of Ashland Chemicals) that ~26~

2667dl-JM3 have a dilution of between 30 to 40 per ce~t monomer (usually styrene) and filler. It is essential that the viscosity range of the final resulting foam material be between 1875 CPS and 2725 CPS
at 25C.

** The acid solution is 1 part acetic acid, 4 parts citric acid, 10 parts water and .5 parts fumed silica gel.
The resulting foam will have a density in the 25 to 30 lb per cubic foot range.
A foam of this density may have particular, but not exclusive application, as a substitute for balsa wood or ply wood.
EXAMPLE TWO
-First Mixture Epoxy-based vinyl ester and monomer mix* 100.00 grams FC - 430 .70 wp DC - 198 .80 wp Dimethyl Anilene .20 wp Dimethyl Paratoluidene .35 wp Cobalt Napthanate .15 wp Sodium Bicarbonate 14.00 wp ~L~?d 6 ~;D ~9 5 2667dl-JM3 Second Mixture Acid Solution** 5.00 wp Benzoyl Paroxide 5.50 wp ~ Some vinyl esters that may be used are DERAKANE - 510N (trade mark of Dow Chemical Canada Inc.), DERAK~NE -510A (trade mark of Dow Chemical Canada Inc.), DERAKANE -XD80804 (~rade mark of Dow ~hemical Canada Inc.), DERAKANE-411 (trade mark of Dow Chemical Canada Inc.), HETRON 922 (trade mark of Ashland Chemicals) that have a dilution of between 30 to 40 per cent monomer (usually styrene) and filler. It is essential that the viscosity range of the final resulting foam material be between 1875 CPS and 2725 CPS
at 25C.
** The acid solution is 1 part acetic acid, 4 parts citric acid, 10 parts water and .5 parts fumed silica gel.

The resulting foam can have a density in the 18 to 25 lb per cubic foot range.
A foam of this density may have particular, but not exclusive application, for use in sandwich boards, building materials, furniture, automobile bodies, home renovations, room additions to residential houses, filler for trailor and truck bodies, marine and floatation products, and filler for airplane bodies.

~65~
2667d1-JM3 E~AMPLE THREE

First Mixture Epoxy-based vinyl ester and monomer mix* 100.00 grams FC - 430 .80 wp DC - 198 .90 wp Dimethyl Anilene .30 wp Dimethyl Paratoluidene .40 wp Cobalt Napthanate .18 wp Sodium Bicarbonate 16.00 wp Second Mixture Acid Solution** 7.00 wp Benzoyl Peroxide 6.00 wp * Some vinyl esters that may be used are DERAKANE - 51ON (trade mark of Dow Chemical Canada Inc.), DERAKANE -510A ~trade mark of Dow Chemical Canada Inc.), DERAKANE -XD80804 (trade mark of Dow Chemical Canada Inc.), DERAKANE-411 (trade mark of Dow Chemical Canada Inc.), HETRON 922 (trade mark of Ashland Chemicals) that have a dilution of between 30 to 40 per cent monomer (usually styrene) and filler. It is essential that the viscosity range of the final resulting foam material be between 1875 CPS and 2725 CPS
at 25C.

2667dl-JM3 ** The acid solution is 1 part acetic acid, 4 parts citric acid, 10 parts water and .5 parts fu~ed silica gel.
The resulting foam can have a density in the 15 to 18 lb per cubic foot range.
A foam of this density may have particular, but not exclusive application, for use in sandwich boards, building materials, furniture, automobile bodies, home renovations, room additions to residential houses, filler for trailor and truck bodies, marine and floatation products, and filler for airplane bodies.

EXAMPLE FOUR

First Mixture Epoxy-based vinyl ester and monomer mix* 100.00 grams FC - 430 .80 wp DC - 198 .90 wp Dimethyl Anilene .30 wp Dimethyl Paratoluidene .50 wp Cobalt Napthanate .18 wp Sodium Bicarbonate 17.00 wp 2667dl-JM3 Second Mixture Acid Solution** 8.00 wp Benzoyl Peroxide 6.20 wp * Some vinyl esters that may be used are DERAKANE - 510N (trade mark of Dow Chemical Canada Inc.), DERAKANE -510A (trade mark of Dow Chemical Canada Inc.), DERAKANE -XD80804 (trade mark of Dow Chemical Canada Inc.), DERAKANE-411 (trade mark of Dow Chemical Canada Inc.), HETRON 922 (trade mark of Ashland Chemicals) that have a dilution of between 30 to 40 per cent monomer (usually styrene) and filler. It is essential that the viscosity range of the final resulting foam material be between 1875 CPS and 2725 CPS
at 25C.
** The acid solution is 1 part acetic acid, 4 parts citric acid, 10 parts water and .5 parts fumed silica gel.
The resulting foam can have a density in the 10 to 15 lb per cubic foot range.
A foam of this density may have particular, but not a~clusive application, for use in sandwich boards, building materials, furniture, automobile bodies, home renovations, room additions to residential houses, filler for trailor and truck bodies, marine and floatation products, and filler for airplane bodies.

~z~
2667d1-JM3 EXAMPLE FIVE

First Mixture .
Epoxy-based vinyl ester and monomer mix* 100.00 grams FC - ~30 .80 wp DC - 198 .90 wp Dimethyl Anilene .40 wp Dimethyl Paratoluidene .50 wp Cobalt Napthanate .20 wp Sodium Bicarbonate 18.00 wp Second Mixture Acid Solution** 9.00 wp ~enzoyl Peroxide 6.50 wp * Some vinyl esters that may be used are DERAKANE - 510N (trade mark of Dow Chemical Canada Inc.), DERAKANE -510A (trade mark of Dow Chemical Canada Inc.), DERAKANE -XD80804 (trade mark of Dow Chemical Canada Inc.), DERAKANE-411 (trade mark of Dow Chemical Canada Inc.), HETRON 922 (trade mark of Ashland Chemicals) that have a dilution of between 30 to 40 per cent monomer (usually styrene) and filler. It is essential that the viscosity range of the final resulting foam material be between 1875 CPS and 2725 CPS
at 25C.

~2G589~i 2667dl-JM3 ** The acid solution is 1 part acetic acid, 4 parts citric acid, 10 parts water and .5 parts fumed silica gel.

The resulting foam can have a density in the 5 to 10 lb per cubic foot range.
A foam of this density may have particular, but not exclusive application, for use in sandwich boards, building materials, furniture, automobile bodies, home renovations, room additions to residential houses, filler for trailor and truck bodies, marine and floatation products, and filler for airplane bodies.
EXAMPLE SIX

First Mixture Epoxy-based vinyl ester and monomer mix* 100.00 grams FC - 430 .80 wp DC - 198 .90 wp Dimethyl Anilene .30 wp ~imethyl Paratoluidene .40 wp Cobalt Napthanate .18 wp Sodium Bicarbonate 16.00 wp ~5~
2667dl-JM3 Second ~ixture _ _ Acid Solution** 7.00 wp Third ~ixture Benzoyl Peroxide 6.00 wp * Some vinyl esters that may be used are DERAKANE - 510N (trade mark o Dow Chemical Canada Inc.), DERAKANE -510A (trade mark of ~ow Chemical Canada Inc.), DERAKANE ~XD80804 (trade mark of Dow Che~ical Canada Inc.), DERAKANE-411 (trade mark of Dow Chemical Canada Inc.), HETRON 922 (trade mark of Ashland Chemicals) that have a dilution of between 30 to 40 per cent monomer (usually styrene) and filler. It is essential that the viscosity range of the final resulting foam material be between 1875 CPS and 2725 CPS
at 25C.
** The acid solution is 1 part acetic acid, 4 parts citric acid, 10 parts water and .5 parts fumed silica gel.
The resulting foam can have a density in the 10 to 15 lb per cubic foot range.
A foam of this density may have particular, but not exclusive application, for use in sandwich boards, building materials, furniture, automobile bodies, home renovations, room additions to residential houses, filler for trailor and truck bodies, marine and floatation products, and filler for airplane bodies.

~6~
2667dl-JM3 In the case of example six, the acid solution and the benzoyl peroxide catalyst were not pre-mixed. It has been aforementioned that the foam may be mixed by first mixing a first misture having the resin, the co-polymerizeable monomer, the surfactants, the hardening accelerators, and the finely dispersed gas releasing salt. Then, a second solution having an acid and a third solution having a peroxide catalyst may be simultaneously mixed into the first mixture to cause foaming in a controllable manner. Example Six, given abovet is mixed in this manner. It should be noted that, although the quantities used in Example Six are the same as those listed in Example Three of this specification, the resulting densities of the foam that may be achieved in Example Six can be lower than those achieved by the use of the pre-mixing employed in Example Three. In Example Six, by not premixing the benzoyl peroxide and the acid solution together before being added to the first mixture, there is no partial pre-absorption of the acid by the benzoyl peroxide catalyst. The acid, in Example Six, therefore is more effective, than in Example Three, and freer to react with the finely dispersed gas-releasing salt to blow the foam.

,. il

Claims

The embodiments of which an exclusive property or privilege is claimed are defined as follows:

1. A process for production of a plastics cellular material comprising:
mixing a first mixture of a fast-curing resin that may be cured with an organic peroxide catalyst, a co-polymerizeable monomer, finely dispersed surfactants, finely dispersed gas releasing salt, hardening accelerators wherein said fast-curing resin and said co-polymerizeable monomer together in combination have a viscosity level in the range of 1875 CPS and 2725 CPS at 25°C;
mixing into the said first mixture an acidic solution for reaction with the gas releasing salt as a blowing agent, and organic peroxide catalysts to form a second mixture that will foam in a controllable manner and cure to produce a foam material of desired density.

2. A process for production of a plastics cellular material comprising:
mixing a first mixture of a fast-curing resin that may be cured with an organic peroxide catalyst, a co-polymerizeable monomer, finely dispersed surfactants, finely dispersed gas releasing salt, hardening accelerators wherein said fast-curing resin and said co-polymerizeable monomer together in combination have a viscosity level in the range of 1875 CPS and 2725 CPS at 25°C;
mixing a second mixture of organic peroxide catalysts and acidic solution for reaction with the gas releasing salt as a blowing agent;

the said two mixtures being combined to form a third mixture that will foam in a controllable manner and cure to produce a foam material of desired density.

3. A process for production of a plastics cellular material comprising:
mixing a first mixture of a fast-curing resin that may be cured with an organic peroxide catalyst, a co-polymerizeable monomer, finely dispersed surfactants, finely dispersed gas releasing salt, hardening accelerators wherein said fast-curing resin and said co-polymerizeable monomer together in combination have a viscosity level in the range of 1875 CPS and 2725 CPS at 25°C;
simultaneously mixing a second solution having an organic peroxide catalyst and a third solution having an acid for reaction with the gas releasing salt as a blowing agent into the said first mixture to form a fourth mixture that will foam in a controllable manner and cure to produce a foam material of desired density.

4. A process as claimed in Claim 1 wherein fillers are included in said first mixture, said fillers being less than 40 w.p. (per 100 w p. unfilled polymers and monomers).

5. A process as claimed in Claim 2 wherein fillers are included in said first mixture, said fillers being less than 40 w.p. (per 100 w.p. unfilled polymers and monomers).

6. A process as claimed in Claim 3 wherein fillers are included in said first mixture, said fillers being less than 40 w.p. (per 100 w.p. unfilled polymers and monomers).

7. A process as claimed in Claim 1 wherein fumed silica gel is added in proportions of between .5 w.p. and 4.5 w.p.
(per 100 w.p. unfilled polymers and monomers).

8. A process as claimed in claim 2 wherein fumed silica gel is added in proportions of between .5 w.p. and 4.5 w.p. (per 100 w.p. unfilled polymers and monomers).

9. A process as claimed in claim 3 wherein fumed silica gel is added in proportions of between .5 w.p. and 4.5 w.p. (per 100 w.p. unfilled polymers and monomers).

10. A process for production of a plastics cellular material as claimed in claim 1 wherein said resin is a vinyl ester having the following configuration:

11. A process for production of a plastics cellular material as claimed in claim 2 wherein said resin is a vinyl ester having the following configuration:

12. A process for production of a plastics cellular material as claimed in claim 3 wherein said resin is a vinyl ester having the following configuration:

13. A process for production of a plastics cellular material as claimed in claim 4 wherein said resin is a vinyl ester having the following configuration:

14. A process for production of a plastics cellular material as claimed in claim 5 wherein said resin is a vinyl ester having the following configuration:

15. A process for production of a plastics cellular material as claimed in claim 6 wherein said resin is a vinyl ester having the following configuration:

16. A process for production of a plastics cellular material comprising the steps of:
mixing a first mixture which consists of a fast-curing acid based vinyl ester resin of the type which can be cured by means of an organic peroxide catalyst, a co-polymerizeable monomer, finely dispersed surfactants and finely dispersed gas releasing salt and hardening accelerators, mixing into the said first mixture a water diluted acidic solution for reaction with the gas releasing salt as a blowing agent, and organic peroxide catalysts to form a reaction mixture that will. foam in a controllable manner and cure to produce a foam material of desired density.

17. A process for production of a plastics cellular material as claimed in claim 16, wherein said fast-curing resin and said co-polymerizeable monomer when combined have a viscosity level in the range of 1875 CPS and 2725 CPS at 25°C.

18. A process for production of a plastics cellular material comprising:
mixing a first mixture of a fast-curing acid based resin that may be cured with an organic peroxide catalyst, a co-polymerizeable monomer, finely dispersed surfactants, finely dispersed gas releasing salt and hardening accelerators, mixing a second mixture of organic peroxide catalysts and acidic solution for reaction with the gas releasing salt as a blowing agent;
the said two mixtures being combined to form a third mixture that will foam in a controllable manner and cure to produce a dense foam material of desired density.

19. A process for production of a plastics cellular material as claimed in claim 18, wherein said fast-curing resin and said co-polymerizeable monomer when combined have a viscosity level in the range of 1875 CPS and 2725 CPS at 25°C.

20. A process for production of a plastics cellular material comprising:
mixing a first mixture of a fast-curing resin that may be cured with an organic peroxide catalyst, a co-polymerizeable monomer, finely dispersed surfactants, finely dispersed gas releasing salt and hardening accelerators, simultaneously mixing a second solution having an organic peroxide catalyst and a third solution having an acid for reaction with the gas releasing salt as a blowing agent into the said first mixture to form a fourth mixture that will foam in a controllable manner and cure to produce a foam material of desired density.

21. A process for production of a plastics cellular material as claimed in claim 20, wherein said fast-curing resin and said co-polymerizeable monomer when combined have a viscosity level in the range of 1875 CPS and 2725 CPS at 25°C.

22. A process as claimed in claim 20, wherein fillers are included in said first mixture.

23. A process as claimed in claim 22, wherein said fillers are less than 40 w.p. (per 100 w.p.. unfilled polymers and monomers).

24. A process as claimed in claim 16, wherein fillers are included in said first mixture, said fillers being less than 40 w.p. (per 100 w.p. unfilled polymers and monomers).

25. A process as claimed in claim 16, wherein fumed silica gel is added in proportions of between .5 w.p. and 4.5 w.p. (per 100 w.p. unfilled polymers and monomers).

26. A process as claimed in claim 18, wherein fumed silica gel is added in proportions of between .5 w.p. and 4.5 w.p. (per 100 w.p. unfilled polymers and monomers).

27. A process as claimed in claim 20, wherein fumed silica gel is added in proportions of between .5 w.p. and 4.5 w.p. (per 100 w.p. unfilled polymers and monomers).

28. A process for production of a plastics cellular material as claimed in claim 16, wherein said resin is a vinyl ester having the following configuration:

29. A process for production of a plastics cellular material as claimed in claim 18, wherein said resin is a vinyl ester having the following configuration:

30. A process for production of a plastics cellular material as claimed in claim 20, wherein said resin is a vinyl ester having the following configuration: