JPH0318807B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method of supplying foam to a cavity. In the manufacture of vehicle bodies that include hollow zones, for example hollow zones of metal, it is sometimes desirable to provide within the hollow zones materials that are believed to contribute to sound deadening, flame retardancy and other properties. Depending on the shape, size and location of the cavity within the hollow zone which is to be loaded with the above-mentioned materials, it may be inappropriate to use blocks, such as preformed foam. If it is desired to fill a cavity of complex shape or of uneven cross-section on a production line, a liquid material flowing into the desired shape is introduced into the cavity and then allowed to solidify or harden to form a suitable filler. It would be appropriate to provide If lightweight or sound deadening properties are desired, it is appropriate to use materials that also foam when introduced into the cavity. In order to avoid corrosion of metal zones, it is advisable to use products as filling materials that do not accelerate the corrosion of metal zones or the deterioration of components within them, such as wires or armored cables, and likewise in hollow zones. It is desirable to use products as filler materials that do not adversely affect other materials present, such as waxes, drawing oils, wires, and the sheath of the cable. The above requirements and other requirements limit the selection of filler materials that can be used. Flowable and foamable at room temperature or slightly elevated temperature, lightweight, sound absorbing and heat resistant.
Additionally, liquids capable of forming curable foams based on silicone materials are available that yield cured products that can be flame retardant. Known compositions typically require several minutes to cure to a free-standing state. When these compositions are used in a hollow metal zone and in contact with the metal zone, curing may be inhibited because the materials in the zone have an adverse effect on, for example, the catalyst used in the composition. There is,
As a result, curing within the hollow zone requires a considerable period of time. Therefore, attempts to use the compositions described above to fill hollow zones with fairly large openings at the lower end may result in the composition flowing out of the openings before the composition has fully cured to a free-standing state. It ended in failure because I put it away. On the other hand, although in some cases it is possible to stop the flow of the composition, this is not always convenient and
Failures associated with inhibition of hardening cannot be eliminated. We have recently found that by first inserting a bag into the hollow zone of a vehicle body and introducing into the bag a liquid silicone-based composition that can form a foam and is curable at ambient temperature, the bag can fit into the hollow zone. It acts to restrict the flow of the composition, and when the composition foams, it promotes integration of the bag into the surface of the cavity, and the bag then acts as a sheath for the cured foam. It has now been found that the composition can be easily filled into the cavity of the hollow zone of a vehicle body without undesirable loss of liquid from the opening of the hollow zone. One aspect of the present invention is a method of dispensing foam into a cavity in a cross-section of a vehicle body, including the step of introducing a bag of flexible material into the cavity and forming a foam curable into a foam elastomer at ambient temperature. and the step of introducing a curable liquid silicone composition into the bag, characterized in that the bag and the composition are selected so that the bag integrates with the shape of the cavity when the composition is foamed. The present invention provides a method for supplying foam to a cavity in a hollow zone of a vehicle body. According to the method of the present invention, the bag provides a membrane within the cavity to limit the flowability of the liquid composition and allows foamable material to be present in the cavity when the composition is converted to its hardened state. Serves to provide a container for the composition to provide a barrier between the composition and the cure inhibitor and to provide a membrane or sheath for the cured foam disposed between the composition and the cavity wall. . The bag has a perimeter that is greater than the perimeter of the cross-section of the cavity to be filled, so that it is flexible enough to stretch and compress so that when the foam is expanded, the bag integrates with the walls of the cavity. selected. The back can be an elastic, inelastic or foamable material that can expand under the action of the composition, but reduces the volume of the foam after it hardens into a solid body in the form of a cavity. It must not have any effect. The method according to the invention can be used for filling or partially filling hollow zones of various dimensions and locations in the body of a vehicle, primarily for the purpose of sound deadening and for restricting the ingress of undesirable substances during use of the vehicle. It is intended for use in filling or closing hollow zones. When using the method of the present invention to close a cavity in a laterally extending hollow zone, the bag restricts the outward flow of the composition, but the bag is not connected to any other downwardly facing inner surface of the cavity. The foamable composition can be selected to allow expansion in the height direction to facilitate integration with the foamable composition. When using the method of the invention to close the cavity of a hollow zone extending in the height direction, the bag restricts the downward flow of the composition but promotes its integration with the interior of the cavity. can be selected to allow lateral expansion of the foam. The mouth of the bag can be closed before the curing reaction is complete, so that the cured foam is completely sealed by the bag, which forms a short barrier across the hollow zone or removes the composition from the surroundings. This is particularly advantageous when it is desired to separate Alternatively, the foam can extend beyond the opening in the barrier, for example, if extending the foam from the hollow zone is desirable or acceptable. Suitable materials for providing a backing should not have a deleterious effect on the curable composition and have sufficient cohesive strength to hold the foam in place when the composition forms a foam, and which can be used to remove foam from the foam. It is a material that is flexible enough to expand under pressure and press against and integrate with the cavity. Bags that are impermeable to the curable composition are preferred. Suitable materials include soft plastic materials such as polyethylene and cellophane. Particularly suitable bags are those formed from tubular extrusions of polyethylene having a thickness of about 0.003 mm to about 0.015 mm. In the method of the present invention, it is possible to form a foam,
A curable liquid silicone composition is used. The composition selected is suitable for use at ambient temperatures, i.e. the temperature in the hollow zone at the time of installation of the bag, for example from about 15°C to about 30°C.
The composition is curable at temperatures in the range of °C. Materials that require the application of significant heat to effect curing within an acceptable period of time impose various additional limitations on various aspects of the operation, including the selection of appropriate heat resistant materials for the bag. Particularly preferred are room temperature curable compositions that foam by evolution of gas during curing. The curable silicone composition preferably consists of a polysiloxane having alkylhydrogensiloxane units and a hydroxylated material, so that the composition can be prepared using a suitable catalyst (for example as described in British Patent No. 798,669). hydrogen gas is released according to the schematic formula ≡SiH+HOQ→≡SiOQ+H ₂ as known in the art under the action of a tin salt of a carboxylic acid or a platinum catalyst as described in GB 1522637. This foams and cures to form a polysiloxane matrix. For example, curable, foam-forming silicone compositions are disclosed in British Patent Nos. 798,669, 867,619 and British Patent Nos.
It is disclosed in the specification of No. 1522637. Hydrogen gas generated during the reaction causes foaming and expansion of the composition as it cures, creating an outward pressure from the composition acting on the bag. If desired, the pressure for foaming or inflating the bag of the composition may be, for example, compressed air, compressed nitrogen, and methane, ethylene,
Hydrocarbons such as ethane, propane and neopentane and methyl fluoride, trifluoromethane,
Augmented by the additional use of blowing agents such as liquefied gases known for use in aerosols containing many fluorinated hydrocarbons such as monochlorodifluoromethane and dichlorodifluoromethane. Can be done. Hydroxylated substances (QOH) are organic substances or silicone compounds with two or more bidroxyl groups per molecule to obtain suitable elastomeric foams. Preferred hydroxylated materials consist of polysiloxanes having silicon-bonded hydroxyl groups. Also, if desired, the hydroxylated material can contain in the composition a polysiloxane having alkenyl groups, such as vinyl groups, which polysiloxane can be platinized for the addition reaction between the alkylhydrogen siloxane and the alkenyl group. It is particularly suitable when a platinum compound imparts flame retardancy using a catalyst. Suitable polysiloxanes with alkylhydrogensiloxane units include polymers with units of the following general formula: In the formula, R each represents a lower alkyl group or a phenyl group, such as a methyl group, and p is 1 or 2.
It is. In addition, alkyl hydrogen polysiloxane has a unit RnSiO _4-o/2 (wherein R has the same meaning as above,
n is 1 or 2 or 3). The curing reaction of suitable compositions depends on the amount of interacting functionalities present and therefore the alkylhydrogen polysiloxane can be selected.
Each R is preferably a methyl group. A preferred end group for the alkylhydrogen polysiloxane has the formula R ₃ SiO _1/2
(Each R represents a methyl group). Suitable alkylhydrogen polysiloxanes contain MeHSiO units with or without Me ₂ SiO units and about
10 ^-6 to about 10 ^-4 m ² /sec, more preferably about 10 ^-6 to about 5
It is an alkylhydrogen polysiloxane with a viscosity of approximately ×10 ^-5 m ² /sec. Suitable polysiloxanes with silicon-bonded hydroxyl or alkenyl groups include polymers containing units of the following general formula: In the formula, each Q is an OH group or a carbon atom number of 2 to
represents _an alkenyl group having 4 atoms, such as a -CH= _CH2 group or a _-CH2.CH2 = _CH2 group, each R represents a lower alkyl residue or a phenyl residue, such as a methyl residue, and m is 1 or It is 2. These polysiloxanes also contain RnSiO _4-o/2 units (wherein R and n have the same meanings as above). These materials are preferably liquids and are selected such that the functionality of the materials is appropriate with respect to the degree of chain extension and crosslinking required during curing of the composition. The polysiloxane having a hydroxyl group bonded to silicon is preferably a silanol group-terminated polydiorganosiloxane represented by the following general formula: In the formula, each R is a methyl group, and n is such that the polysiloxane has a viscosity of about 5 x 10 ^-4 to 2.5 x 10 ^-2 m ² /sec, or a number average molecular weight of about 20,000 to about 80,000. It is a value. A suitable material is approximately 1.5×10 ^-3
It has a viscosity of ~1.5×10 ^-2 m ² /sec and has one unit represented by the general formula R ₂ SiO and one unit represented by the general formula R ₂ (OH)SiO _1/2 per molecule. Contains 2 units of. Polysiloxanes having silicon-bonded alkenyl groups preferably include polysiloxanes in which alkenyl groups provide up to about 5% of the total silicon-bonded organic groups of the polymer. The alkenyl group is attached to the terminal silicon atom of the polysiloxane chain, or
or bonded to silicon atoms along the polysiloxane chain, or both.
Suitable alkenylpolysiloxanes terminated with dimethylvinyl groups, e.g. about 8.5 x 10 ^-2 m ² /
Polysiloxanes with viscosities up to 2.5 seconds and terminated with phenylmethylvinyl groups, e.g.
Includes polydimethylsiloxanes having a viscosity of x10 ^-4 to about 10 ^-2 m ² /sec. In a suitable substance,
Each R group is a methyl residue. Thus, in compositions suitable for the present invention, the preferred hydroxyl-functional polydimethylsiloxanes and alkenyl-functional polydimethylsiloxanes result in polysiloxane chain lengths that are significant in the product obtained from curing of the compositions. It is desirable from the viewpoint of the flexibility and rubber-like elasticity required for Also, if desired, relatively low molecular weight or short chain organic difunctional polysiloxanes can be included in the composition. Suitable materials include α,ω-dihydroxypolydimethylsiloxanes having up to 25 dimethylsiloxane units in the chain. Also, a predetermined amount of a higher functionality substance can be included in the composition as a crosslinking agent. Suitable crosslinking agents include materials having three or more functional groups, such as hydroxyl groups, per molecule.
Suitable crosslinking agents are alkoxysilanes and/or condensation products thereof, such as methyltrimethoxysilane, n-propylortho, which are capable of condensing with three or more hydroxypolysiloxane molecules by releasing the corresponding alcohol of the alkyl residue. silicates and ethyl polysilicate. Compositions for use in the present invention preferably contain monofunctional hydroxysilicone compounds that are effective as chain terminators. The material influences the structure of the foam formed by use of the composition, and the use of the material is highly preferred primarily when open cell foam is desired. Suitable monofunctional hydroxy compounds are triorganosilanols and organosilanols, which can be, for example, short chain siloxanes having, for example, up to about 25 siloxane units per molecule and having bidrocykyl end groups or hydroxyl side chains, or organosilanols of the general formula R ₃ SiOH, in which each R can be, for example, a lower alkyl group, such as a methyl group or a phenyl group. An example of such a substance is HO(CH ₃ ) ₂ Si
[OSi( _CH3 ) ₂ ] _3CH3 ( _{nonamethyltetrasiloxane} -1-ol),

[Formula] (heptamethyltrisiloxan-2-ol) and CH ₃
Includes (C ₆ H ₅ ) ₂ SiOH (diphenylmethylsilanol). It is desirable to incorporate a filler into the composition used in the present invention. Preferred fillers include, for example, metal oxides, clays, fumed silicas, hydrophobic silicas, such as those prepared by treating finely divided silica with organochlorosilanes, organosiloxanes, organosilazanes or alkylsilanols. Both silica and powdered glass can be used. The advantages arising from the use of the method of the invention arise primarily from the control of the flow of the composition by the bag and the separation of the composition by the bag and the hollow zone before the composition hardens to a self-supporting state. For example, it is possible to apply a prescribed amount of the composition to the hollow zone extending in the height direction without allowing the composition to flow out from the hollow zone before the composition has hardened. The possibility of inhibiting hardening of the composition and other deleterious effects that may occur due to the material of the hollow zone or the material above the hollow zone can be ignored. Similarly, compositions may be used that, in the absence of a bag, may have an undesirable effect on the hollow zone or other contents of the hollow zone. Furthermore, uniform filling of the cavity can be accomplished repeatedly with little operator attention after introduction of the bag and liquid composition into the cavity of the hollow zone. Still other advantages achieved by using the method of the present invention include improving the moisture permeation resistance of the foam when using moisture impermeable bags. The method according to the invention can be used for partially or completely filling cavities in hollow sections of vehicle bodies, and is primarily used for sound deadening automobiles or trucks with fairly long tubular sections with open ends. has value. It is particularly valuable in the above-mentioned positions when it is important to minimize the wastage of filling material from the hollow zone extending in the height direction or to obtain satisfactory results without increasing the operating precautions. be. That is, when manufacturing automobiles on a production line, it can be expected to be particularly valuable in processing, for example, door supports, so-called A pillars. In order to make the present invention more clear, examples according to the present invention are described below for the present invention and its explanation. In the examples, compositions A and B were used, which are foam-forming and curable compositions that are fluid liquids based on silicone materials. Composition A was a two-component room temperature curable silicone composition formed by mixing equal volumes of components 1 and 2 consisting of the following materials:

[Table] When Components 1 and 2 are mixed, Composition A foams and cures at room temperature to form a medium density (approximately 170-220 Kg/cm ³ ) foam with good heat resistance, thermal insulation and sound insulation properties, for example. Obtained. Composition B was a two-component room temperature curable silicone composition formed by mixing 7 parts by weight of tin octoate with a composition consisting of the materials described below: (% by weight) α, ω Hydroxypolydimethylsiloxane, molecular weight approx. 21000 (viscosity = approx. 2 x 10 ^-3 m ² /sec) 100 α, ω Hydroxy polydimethylsiloxane, molecular weight approx. 900 (viscosity = approx. 4.2 x 10 ^-5 m ² /sec) 10 Diph Enylmethylsilanol 10 Methylhydrogensiloxane terminated with trimethylsiloxy groups (viscosity = approx. 3 x 10 ^-5 m ² /s) 10 Fine powder filler 25 n-propyl orthosilicate 4 Mix the above composition with tin octoate Then,
Composition B foams and cures at room temperature to a low density (approximately
120-200Kg/cm ³ ) foam was obtained. Example 1 3 was formed by sealing one end of a tubular polyethylene film with a thickness of 0.006 mm and a circumference of 230 mm.
A rectangular bag with sealed ends and a width of 115 mm.
250ml beaker (circumference 203mm, radius 32.3mm and height
77mm) was loaded so that the opening of the bag matched with the mouth of the beaker. Composition A was mixed and poured into a bag in a beaker. The composition foamed and hardened into a medium density foam in the bag as the bag was pressed firmly against the inner wall of the beaker. No evidence of inhibition of curing by polyethylene was observed. Similar results were obtained for composition B compared to composition A.
It was also obtained when used instead of . Example 2 3 was formed by sealing one end of a tubular polyethylene film with a thickness of 0.006 mm and a circumference of 280 mm.
A rectangular bag with sealed ends and a width of 140 mm.
A rectangular transparent Perspex tube with a cross section of 76.2 mm x 50.8 mm and a height of 200 mm was loaded. Both ends of the perspex tube were open. The tube was placed with the length of the cavity extending in the height direction, and the bag was loaded into the top half of the perspex tube with the mouth of the bag near the top opening. Composition A was mixed and poured into the mouth of the bag. The composition was mixed sufficiently so that the foam produced extended above the mouth of the bag. The bottom surface of the bag prevented the composition from flowing downwardly out of the bag. When the composition foams,
The bag was pressurized to integrate with the shape of the rectangular tube, and the composition cured to adhere the bag to the inner wall of the perspex tube. Example 3 A Perspex tube similar to that described in Example 2 was used except that it had a 10 mm diameter hole in one side approximately 100 mm from the bottom of the Perspex tube. A rectangular bag having three ends sealed and having a width of 140 mm, formed by sealing one end of a tubular polyethylene film having a thickness of 0.006 mm and a circumference of 330 mm, was inserted into the perspex tube through the hole described above.
The mouth of the bag was held on the outside of the Perspex tube. Composition B was mixed and poured into the inside of the bag through the bag mouth. When the composition foams and the composition expands, the bag integrates the cavity of the tube as far as the bag extends along the tube. The composition cured to form a foam and the tube was sealed by sealing the bag inside the tube. Example 4 In this example, the cavity of a vertical door post of a vehicle was filled with foam during vehicle manufacture. The door support is a support of conventional construction and comprises a hollow zone of generally rectangular cross-section with a circumference of approximately 150 mm, the hollow zone being open at the bottom. The hollow zone contained PVC (vinyl chloride) coated wires, wiring harnesses which usually consisted of remnants of extraction oil and other contaminants. A bag similar to that used in Example 3 and having a length of 200 mm was introduced into the cavity formed by the inner surface of the hollow zone and the outer surface of the wiring harness inserted through the hole in the post. The mouth of the bug was held on the outside of the post. Composition B was mixed and injected into the cavity through the mouth of the bag. The composition flowed down into the bag in the cavity as far as the bag expanded, foamed, and cured to close the post, and the bag was attached to the post wall and wiring harness by the cured foam. Batsugu's mouth was cut off.

Claims (1)

[Scope of Claims] 1. A method for supplying a foam into a cavity in a cross-section of a vehicle body, including the step of introducing a bag of flexible material into the cavity and forming a foam curable into a foam elastomer at ambient temperature. and the step of introducing a curable liquid silicone composition into the bag, characterized in that the bag and the composition are selected so that the bag integrates with the shape of the cavity when the composition is foamed. A method for supplying foam to a cavity in a hollow zone of a vehicle body. 2. The method of claim 1, wherein the composition comprises a polysiloxane having alkylhydrogensiloxane units, a hydroxylating material, and a catalyst. 3. The method of claim 2, wherein the hydroxylated material comprises a polysiloxane having hydroxyl groups bonded to silicon. 4. The method according to claim 2, wherein the catalyst comprises a tin salt of a carboxylic acid. 5. The method according to claim 2 or 3, wherein the composition comprises a polysiloxane having an alkenyl group bonded to silicon, and the catalyst comprises a platinum compound. 6. A method according to any one of claims 1 to 5, wherein the bag is formed from a polyethylene film having a thickness of 0.003 to 0.015 mm.