WO2003000823A1

WO2003000823A1 - Composition for molded fire stop

Info

Publication number: WO2003000823A1
Application number: PCT/CA2002/000949
Authority: WO
Inventors: Frank Xing; Brian Didone; Manfred Harle
Original assignee: Royal Group Technologies Limited
Priority date: 2001-06-22
Filing date: 2002-06-25
Publication date: 2003-01-03
Also published as: WO2004041967A1; WO2003000824A1; AU2002315605A1; CA2351262A1; EP1404780A2; EP1404781A1; EP1456324A1; WO2003000823A8; AU2002344883A1

Abstract

The present invention is directed to a composition which can be molded into a fire stop. The composition comprises 100 parts by weight of a moldable resin and 20 to 100 parts by weight of an intumescent material, preferably exfoliated graphite. The composition may optionally contain other typical components utilized in molding operations for resins such as lubricants, foaming agents, plasticizers, modifiers and processing aids.

Description

TITLE: COMPOSITION FOR MOLDED FIRE STOP

FIELD OF THE INVENTION

The present invention relates to a composition which can be molded into a fire and smoke block for preventing the spread of fire through openings or penetrations in the walls and floors of buildings.

BACKGROUND OF THE INVENTION

It has long been known by those skilled in the art that fire and smoke will move very rapidly between different areas in a building even when those areas are 15 separated by separations or partitions such as walls, ceilings and floors . Typically these separations or partitions are penetrated by things such as pipes, ducts, wires, etc. and the fire and smoke will travel along the outside of the penetrating member where it fits through 20 an opening or aperture in the separation. Accordingly, it is extremely important that these conduits include fire blocks or fire stop devices.

Fire stop devices are used to prevent fire from 25 spreading from one room to another through openings or apertures in a partition such as a wall, floor or ceiling through which a pipe passes . The purpose of the fire stop device is to close off the opening in the partition in the event of a fire. The fire stop device generally 30 contains an intumescent material which expands when the temperature reaches a certain level. The expansion of the intumescent material is directed inwardly toward the pipe and crushes the pipe which is generally softened by the temperatures encountered in a fire and closes off the 35 opening in the wall with a hard char. A number of fire stop devices have been proposed requiring field installation whereby for example foil lined strips of intumescent material are wrapped around a plate and then a restraining collar is wrapped around the 5 intumescent material and secured by screws or straps . Examples of many such fire stops are provided in amongst others U.S. patent 5,498 466, 5,953,872, 5,634,304, 5,390,465, and 5,076,309. The installation of such fire stop devices can be labor-intensive and requires that they be properly sealed in the opening to fulfill their function.

SUMMARY OF THE INVENTION

The present invention relates to a composition which can be molded to form a fire stop device. The composition comprises 100 parts by weight of a moldable resin, 5 to 30 parts by weight of an intumescent 20 material, preferably exfoliated graphite and 1 to 5 parts by weight of a blowing agent. The composition may optionally contain other typical components utilized in molding operations for resins such as lubricants, plasticizers, modifiers and processing aids.

In an aspect of the invention, the composition comprises 100 parts by weight of a moldable resin, 15 to 25 parts by weight of an intumescent material, and 1 to 3 parts by weight of a foaming or blowing agent .

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is directed to composition which may be used to mold fire stop devices, such as couplings for use with PVC and other plastic pipe to bridge an opening in a wall and function as a fire stop for the opening as is described below. The composition comprises 100 parts by weight of a suitable moldable 5 resin, 5 to 30 parts by weight of an intumescent material, preferably exfoliated graphite and 1 to 5 parts by weight of a blowing agent. The combination of the intumescent and blowing agent provides a product which expands to many times its volume upon being exposed to heat such as is generated in a fire situation. Depending upon the nature of the object to be molded and its intended use, other optional ingredients may be added such as lubricants, plasticizers, modifiers, and processing aids.

The suitable moldable resin is utilized as a base for the molded product to carry the intumescent material and eliminate the need for separate intumescent components which would increase the cost and complexity 20 of installations requiring fire blocks. The moldable resin is a resin which is typically suitable for forming into products by conventional molding operations, particularly injection molding. Typically the resin will be selected from ABS, polyethylenes, polypropylenes,

25 polycarbonates, polyvinylchlorides, or acrylic resins such as styrenes or MMA. Preferably, the moldable resin is a polyvinylchloride. The moldable resin maybe virgin material or it may be derived from recycled material.

The intumescent material may be any of the commonlyemployed intumescent materials so long as they are compatible with the moldable resin utilized as the base material. Such commonly employed intumescent materials include silicate and graphite based materials, preferably graphite based materials, most preferably exfoliated graphite.

The foaming or blowing agent is utilized to provide for increased expansion of the char produced when the fire block formed of the composition of the present invention is exposed to the heat of a fire. By utilizing a foaming or blowing agent, the amount of intumescent material required to produce a char of the required

10 dimension to block off the opening is reduced. This is of particular utility where the nature of the selected intumescent is such that it increases the difficulty of the molding operation used to produce the final product or where the cost of the intumescent is high. In these situations, the addition of the foaming or blowing agent can significantly reduce the amount of the intumescent material of the composition. The foaming or blowing agent is selected such it will become activated at or near the temperatures typically encountered in a fire situation.

The amount of intumescent material and blowing agent utilized in the composition is selected based upon the nature of the product to be molded and its intended use as well as the characteristics of the intumescent material and blowing agent. The amount of the intumescent material and blowing agent is selected to provide the molded product with the desired fire stop properties such that when the product is subjected to the heat of a fire, the intumescent material intumesces and the blowing agent expands by producing gas and blocks off the opening in the partition it is protecting. The factors that will affect the selection of the amount of intumescing material and blowing agent include the size and volume of the molded product, the intumescing properties of the intumescent material, the expansion characteristics of the blowing agent and the presence of other optional components in the composition as will be explained further below.

Generally, the amount of intumescent material in the composition will be between about 5 and 30 parts by weight, preferably between about 10 and 25 parts by weight, more preferably, between about 15 and 25 parts by weight, most preferably, between about 15 and 20 parts by weight, based upon 100 parts by weight of the resin in the composition.

The amount of the blowing agent in the composition is generally between about 1 and 5 parts by weight, preferably between about 1 and 4 parts by weight, more preferably between about 1 and 3 parts by weight . The amount of blowing agent in the composition is selected in 20 an inverse relation to the amount of intumescent. Thus as the amount of blowing agent is increased, the amount of intumescent is reduced.

The composition may contain other optional ingredients including many of the commonly utilized ingredients of moldable compositions. The optional ingredients are typically one or more ingredients selected from lubricants, plasticizers, modifiers, and processing aids .

The lubricants are utilized to improve the movement of the composition through the pathways of the molding machine. This is of particular use where the nature of the intumescent material is such that it may make the composition more difficult to move through the molding machine. In these situations, the use of one or more lubricants aids the movement of the composition through the machine and reduces the operating pressure. Typically the one or more lubricants are selected from long chain fatty acids and their salts such as stearic acids and their salts . The lubricants may be present in an amount of up to about 5.0 parts by weight .

The modifiers such as impact modifiers are utilized to improve the physical characteristics of the molded product. For example, acrylic impact modifiers in an amount up to about 10 parts by weight may be utilized toimprove the impact resistance of the molded product.

Other optional and commonly utilized additives inmolding operations such as plasticizers and processing aids may be employed in the usual amounts .

In a particularly preferred embodiment the composition is utilized to injection mold fire stop couplings and comprises 100 parts by weight of a moldable resin, 10.0 to 25.0 parts by weight^" exfoliated graphite, 1.2 to 2.5 parts by weight of a blowing agent, 1.5 to 3.0 parts by weight of one or more stabilizers, 0 to 5.0 parts by weight of one or more lubricants, 0 to 10 parts by weight of one or more modifiers, and 0 to 5.0 parts by weight of one or more processing aids. A particularly preferred composition for injection molding contains 100 parts by weight of PVC resins, 2.5 parts by weight of one or more stabilizers, 4.9 parts by weight of one or more lubricants, 8.0 parts by weight of an acrylic modifier, 3.0 parts by weight of acrylic processing aid, 25 parts by weight of exfoliated graphite and 1.2 parts by weight of a foaming agent.

Another preferred composition according to present invention contain 110 parts by weight of PVC resins, 2.5 parts by weight of stabilizers, 15.0 parts by weight of exfoliated graphite, 2.4 parts by weight of foaming agent, 5.8 parts by weight lubricants, 1.5 parts by weight processing aid and 8.0 parts by weight of acrylic impact modifier.

The compositions according the present invention are prepared in a generally conventional manner with some modifications due to the nature of the ingredients by mixing the components of the compositions together and 15 then molded in a suitable operation to form the fire stop devices of the present invention. Typically, the molding operation involves mixing the components of the composition with the application of sufficient heat to melt the components such that they can be injected into 20 the molding machine. Due to the nature of the intumescent and blowing agent, the mixing temperature is selected to be below the activation temperature of these ingredients .

Once the components are properly mixed, the composition is injected into a suitable mold to form the final product. The composition is generally injected under pressure and at a temperature to allow the final product to be homogeneously produced. It has been found that due to the nature of the intumescent material and blowing agent, a very slow injection speed is desired to prevent excessive gas build-up and entrapment. To further reduce gas build-up, the mold is vented during final mold fill and pressurization. In order maintain the desired shape of the final product and prevent premature material expansion upon release from the mold, the product is maintained in the mold for a longer cooling time than is typical in injection molding operations .

The following examples are intended to illustrate the invention but the invention is not limited thereto .

100 kg of PVC resin was placed in a mixer and then 2.5 kg of PVC stabilizer and 1.2 kg of foaming agent added. The mixer was started and the components blended to 70 deg C. At 70 deg C, 8.0 kg of acrylic impact modifier, 4.9 kg of lubricants, and 3.0 kg of processing aid were added, the mixture blended to 100 deg C and then the mixer stopped. 25.0 kg of exfoliated graphite was added and the mixture blended for 90 seconds. The mixture was utilized to injection mold a 2 inch coupler for use as a fire stop for PVC pipe. The injection operation utilized barrel temperatures of 360 deg F, 350 deg F and 340 deg F for the front, middle and rear zones respectively. The material was injected into suitable molds at a slow injection speed with a high pressure of about 2000, psi. The material was held in the mold for 30 seconds at a holding pressure of 1200 psi. The back pressure was 40 psi with a very slow screw rotation and a long cooling time.

110 kg of PVC resin was placed in a mixer and then30 2.5 kg of PVC stabilizer and 2.4 kg of blowing agentadded. The mixer was started and the components blended to 70 deg C. At 70 deg C, 8.0 kg of acrylic impact modifier, 5.8 kg of lubricants, and 1.5 kg of processing aid were added, the mixture blended to 100 deg C and then the mixer stopped. 15.0 kg of exfoliated graphite was added and the mixture blended for 90 seconds. The mixture was utilized to injection mold a 2 inch coupler for use as a fire stop for PVC pipe. The injection operation utilized barrel temperatures of 360 deg F, 350 deg F and 340 deg F for the front, middle and rear zones respectively. The material was injected into suitable molds at a slow injection speed with a high pressure of about 2000 psi. The material was held in the mold for 30 seconds at a holding pressure of 1200 psi. The back pressure was 40 psi with a very slow screw rotation and a long cooling time.

The fire stop devices prepared as described abovel5 are utilized to bridge openings in partitions such that when the device is exposed to the high heat of a fire, the intumescent material such as the exfoliated graphite expands to close off the opening in the partition to prevent the spread of fire through the opening. The amount of foaming agent and intumescent material in the compositions can be adjusted to give the proper amount of expansion to close off the opening upon exposure to the heat of the fire. By providing the fire stop as a coupling it is not necessary to install additional fire 25 stop material when a PVC pipe bridges an opening.

Rather, the fire stop coupling is used to join two pieces of PVC pipe together through the opening. This makes the installation of the piping systems much easier and reduces costs associated with pipe installations.

The composition of the present invention is of particular use in a piping system comprising a pair of pipes to be coupled by a coupler which joins the pipes where they pass through a partition or wall. The coupler includes a pair of sockets to opposite ends of the coupler for receiving the ends of the pipes to be joined and a wall region between the pair of sockets having a thickness greater than the sockets and an internal diameter less than that of the sockets.

The pipes have a standard plastic construction made from material such as PVC which is additionally a preferred constituent of the coupler. In the coupler the 10 PVC provides a carrier for the intumescent material such as graphite which gives the coupler its intumescent properties .

The benefit of making the coupler of the same material as that used in the pipes, i.e. PVC, is that the pipes can be welded to the coupler using standard solvents . Further both the pipes and the coupler have the same physical characteristics so that all components of the system react in the same manner to outside forces to help the system stay together. In addition there are no contamination problems as there can be when parts of a plastic system are made from different materials.

When subjected to excessive heat e.g., heat created by a fire or the like, the intumescent material making up the coupler when subjected to this heat, rapidly expands from its original shape to a much larger mass of material. The expansion of the intumescent material is many times its original size and the expansion is in the direction of the source of the heat which will stop the fire before it has a chance to spread. The expanded material completely closes down the passage through the coupler and further completely seals off the passage around the pipe system through the wall. Accordingly, the intumescent material effectively seals off one room area from the next along all areas internally and externally of the pipe system. As will be appreciated from the description^— above the installation of the pipe and the fire and smoke block is done in a very time efficient manner. This is an obvious advantage during the building setup. Furthermore, 5 the actual operation of the fire and smoke block is also extremely efficient as described.

Although various preferred embodiments of the present invention have been described herein in detail, 10 it will be appreciated by those skilled in the art that variations may be made thereto without departing from the spirit of the invention.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A composition for molding into a fire stop coupling, the composition comprising 100 parts by weight of a moldable resin, 5 to 30 parts by weight of an intumescent material and 1 to 5 parts by weight of a blowing agent .

2. A composition according to claim 1 wherein the composition further includes up to 10 parts by weight of one or more lubricants, up to 10 parts by weight of one or more modifiers, and up to 5.0 parts by weight of one or more processing aids.

3. A composition according to claim 1 comprising 100 parts by weight PVC resin, 10 to 25 parts by weight exfoliated graphite, 1 to 3 parts by weight of blowing agent, 2.0 to 2.5 parts by weight stabilizers, 0 to 6.0 parts by weight lubricants, 0 to 8.0 parts by weight acrylic modifier, and 0 to 3.0 parts by weight acrylic processing aid