JPS5843262B2 - How to make a laminated pneumatic tire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pneumatic tire having a portion without reinforcing fabric;
More particularly, the present invention relates to a laminated pneumatic tire that includes a hard layer and a soft layer arranged to provide high resistance to flex cracking.

It has long been recognized in the pneumatic tire industry that fabric-reinforced tires have a number of drawbacks and that it would be desirable to make fabric-free tires that could be manufactured using less expensive procedures.

Conventional methods of tire construction are slow and expensive, requiring separate handling and processing of one or more types of rubber and/or cord fabric for each tire, calendering and handling of individual plies, and In addition to requiring final manual assembly, conventional tire construction is not easily adapted to any type of automation that would reduce labor costs and improve tire quality and uniformity.

An additional source of excessive manufacturing costs associated with conventional tire construction is, first of all, the large amount of heat required to cure a green tire, one at a time, for about 12 to 20 minutes or more. Second, a large amount of space is taken up by rubber processing and mixing equipment such as rolling mills, pan burrs, extruders, calenders, and tire building machinery.

Other problems with conventional fabric-reinforced tires include the difficulty in uniformly placing the many elements of the tire and obtaining uniform inflation from a cylindrical shape on a flat drum to a final toroidal shape. This is the difficulty of

The laminated tire of the present invention eliminates some of these problems.

In the search for methods of tire contouring and construction that do not require lamination of cord and rubber compounds and subsequent manual fabrication of ply layers, the tire manufacturing industry is developing tire contouring and construction methods that do not require the manual fabrication of cord and rubber compound laminations and subsequent ply layers. Force - U.S. Patent No. 2 has attempted to create the waste portion into a desired shape.
,902,072 has a tread,
Consists of inner and outer walls and polyurethane in a cell-like shape filling the space between the inner and outer walls.

U.S. Pat. No. 3,208,500 discloses the fabrication of the carcass portion of a pneumatic tire by molding polyurethane or polyamide into a single, generally uniform layer.

US Pat. No. 3,274,322 discloses a method of forming a flow-forming material, such as polyurethane, into a piece of material that can later be formed into a tire carcass using a doctor blade.

U.S. Pat. No. 3,386,485 discloses that any of a number of suggested polymers and copolymers may be formed by molding the annular halves of the tire separately and then molding the two halves together in different presses. exemplifies how to make a clothless pneumatic tire from one of the following.

US Pat. No. 3,396,773 illustrates the application of centrifugal casting techniques to form tires that are described as being solid rather than air.

The general concept of centrifugal cast molding was introduced in US Pat. , 555, 141, has been applied to pneumatic tires.

Due to the rotation of the mold, the polyurethane flows and covers all the inner surfaces of the mold, and the stationary plate, which has the same shape as the inside of a tire, serves to spread the material in the same way as a doctor blade.

U.S. Pat. No. 3,701,374 discloses a fabricless tire carcass made from polyurethane elastomers, other elastomers, and a method of making the tire that provides the necessary physical properties.

To the extent appropriate, the above-identified United States patents are herein incorporated by reference as background information to supplement the detailed description that appears below.

While many of the problems associated with conventional tire construction can be reduced or eliminated by the construction of tires according to the prior art patents mentioned above, cast tire profiles such as the molds proposed in these patents suffer from a number of significant problems. Problems have prevented the use of such special tires from becoming widespread.

A major problem with cast tires in terms of tire life is what is known as bending fatigue defects.

Under the weight of the car, the part of the tire in contact with the ground is deformed as a result of the continuous bending of the rubber during operation of the tire.

In conventional fabric-reinforced tires, the fabric can withstand, for example, low inflation pressures of less than 85% and 15% rubber.

If the fabric is to be removed without changing the general shape of the tire, it may be necessary to use a higher modulus rubber to allow the tire to maintain its shape; however, harder rubber will Has a relatively short life due to fatigue defects.

For example, whenever a small crack or defect results from a micro-nick or notch from a sharp object, the crack tends to develop and grow during continuous bending until the tire becomes weak and dangerous.

When using fabric reinforcement, it is possible to use softer rubber that does not have significant bending fatigue problems.

However, when making clothless tires using the stiffer polymers required to obtain the necessary strength, bending fatigue problems are extremely significant.

Experimental data on tires without fabric seem to indicate that sidewall cracking is the primary form of defect.

The improved tire incorporates a series of layers of polymeric material having a relatively low tensile modulus and a tensile modulus of 5.0
00~50,000 pounds (351,5~3515ky)
The present invention provides a novel laminated tire carcass structure that uses multiple layers of polymeric materials with relatively high tensile modulus, such as (cI/L).

The layers are arranged in an alternating pattern in such a way as to provide an overall tire carcass with the desired strength and stiffness, while at the same time providing a much lower resistance to bending fatigue defects than would be obtainable from a homogeneous construction. It is preferable.

The tires of the present invention are preferably made from fluid polymeric materials having a viscosity at processing temperatures such that they can flow and form the desired layers of the tire for a reasonable period of time.

Rotary casting methods can be used in fluid polymerization as well as other forming methods.

When using fluid polyurethane polymers, the preferred method of forming the tire is to provide a mold with the desired annular shape of the tire and apply a generally uniform layer of polymeric material to the inside surface of the mold. , then curing that layer, or at least partially curing it, and then applying a next generally uniform layer with a different modulus.

A number of layers are applied and cured in this manner until the desired thickness is obtained.

A doctor blade may be used to form the layer or to provide a uniform thickness, and relative rotation may be provided between the mold and the blade to achieve this.

When the fluid polymeric material is applied from a spray nozzle or other applicator, relative movement may be applied to the mold during application of the fluid polymer, e.g. by rotating the mold relative to the applicator or vice versa. and the applicator.

If desired, the fluid materials can be formulated and handled so that the necessary curing of one layer can occur during only one or two revolutions of the mold prior to application of the next layer.

The rotary casting process forms many different layers of polyurethane polymer or other suitable polymer at varying thicknesses from 0.001 inch to 0.1 inch (0.0254 to 2.54 mm). can be used to

Although the hard and soft layers preferably alternate, many different arrangements are possible which will provide the desired resistance to bending and cracking.

When making pneumatic tires by the above method from fluid polyurethane polymers, the tensile modulus and hardness of the different layers are:
Variations can be made by varying the amount or type of curing agent used and the molecular weight or type of urethane polymer used.

Referring in detail to the drawings, which are for the purpose of illustrating, and not for the purpose of limiting, a preferred embodiment of the invention, FIG. A pneumatic tire 10 is shown.

It is understood that FIG. 1 is partial and schematic and that conventional annular reinforcing belts or other reinforcing means may be provided to the tread portion 12 without providing commercialization or other reinforcement within the sidewall portions 14. be understood.

In other words, the cross-section of the tire is U.S. Patent No. 3.701
, 374 or other patents mentioned above.

Although the tire preferably has a toroidal cross section, the present invention provides
It will also be appreciated that it applies to the special cross-section tires described in the embodiments of U.S. Pat. No. 3,840,060.

Conventional means may be provided on the tire or on the vehicle to strengthen the bead portion of the tire or to help hold it in place on the vehicle rim.

The tire 10 of the present invention is preferably formed with a substantial number of layers of polymeric material, each layer preferably having a generally uniform thickness and completely covering adjacent layers.

In the specific example of FIG. 2, the tire carcass and side wall portion 14
each consists of 13 stacks formed of alternating high and low index layers H and L.

A low-rate layer is applied to both the inner and outer surfaces of the tire,
Any other layer contains a high proportion of layer H.

This particular profile makes it possible to obtain a tire of desired tension and stiffness through the use of high modulus layers, while at the same time minimizing the tendency to bend and crack.

It will be appreciated that although thirteen layers are often preferred, different numbers of layers may also provide good results.

FIG. 3 also illustrates a different embodiment having 13 layers, in which a medium layer M is provided in addition to the high modulus layer H and the low modulus layer.

This arrangement is intended to illustrate a preferred embodiment of the invention and is not intended to limit the invention.

Referring to the drawings in more detail, FIG.
A pneumatic tire 10 consisting of a side wall portion 14 and two side wall portions 14 is illustrated.

FIG. 1 is partially illustrative and shows that a conventional peripheral reinforcing belt or other reinforcing means may be provided in the tread portion 12 without providing fabric reinforcement or other reinforcement in the sidewall portion 14. is understood.

In other words, the tire cross-section is generally
No. 01,374 or as shown in other patents mentioned above.

Although it is preferred that the tire have a toroidal cross-section, it is also understood that the invention also applies to tires of special cross-sections such as those illustrated in the examples in U.S. Pat. No. 3,840,060. Will.

Conventional means may be provided on the tire or wheel for reinforcing the bead of the tire or for holding the tire in its position on the wheel rim.

The tire 10 of the present invention is preferably made of a number of layers of polymeric material, each layer preferably having a generally uniform thickness and completely covering adjacent layers. .

In the specific example shown in Figure 2. Tire carcass and each side wall part 14
consists of a 13 layer stack made of alternating high and low modulus layers H and L.

A low modulus layer is provided on both the inner and outer surfaces of the tire, and every other layer consists of a high modulus layer H.

This particular configuration makes it possible, through the use of high modulus layers, to obtain a tire of the desired strength and stiffness, while at the same time minimizing the tendency to bend cracks.

It will also be appreciated that although 13 layers are often desirable, different numbers of layers can also give good results.

FIG. 3 likewise illustrates a different embodiment with 13 layers, in which a medium modulus layer M is provided in addition to the high modulus layer H and the low modulus layer.

This arrangement is similar to that of FIG. 2 in that the layers H and L alternate regularly and have low modulus layers on the inner and outer surfaces of the tire.

However, the medium modulus layer M is the layer H closest to each layer.
is established between.

This allows the use of very high modulus layer H without large abrupt changes in modulus when passing from layer H to layer H.

If the tire has a large number of layers, such as 25 to 50 or more, it may be desirable to provide one or more intermediate modulus layers between the low modulus layer and the high modulus layer.

FIG. 4 illustrates another embodiment of the invention, in which in the center of the laminate structure the low and high modulus layers alternate as in FIG. 2, and some outer layers have the same modulus. Made of modulus material.

In this figure, the first three layers on both the inside and outside of the carcass are low modulus layers.

One reason for using this type of configuration is that the inner and outer surfaces of the tire are subject to greater bending strains, which lower modulus materials withstand better.

FIG. 5 shows another embodiment of the invention, in which the various layers have different thicknesses.

Second. In the embodiments of FIGS. 3 and 4, all layers are shown as having the same thickness.

It will be appreciated, however, that some thickness variation may be provided and that it is often desirable to have the low modulus layer be of somewhat greater thickness than the high modulus layer.

In the embodiment of FIG. 5, the low and high modulus layers alternate regularly as in FIG. 2, except that the inner surface of the carcass is provided with two low modulus layers.

A number of different methods can be used to make tires according to the present invention.

An uncured tire is manufactured by forming a cylindrical laminate having, for example, 10 or more layers, and then expanding the laminate from a cylindrical to a toroidal shape in a manner somewhat modeled on common flat band methods. can do.

Tires can also be formed by applying layers to the laminate while the laminate is toroidally formed and has any other desired cross-section, as described below.

The first tire made according to the invention consisted of:
It is created by manually applying a layer of a fluid polymeric material of fairly uniform thickness onto the exterior surface of a metal mold.

Another possible tire construction method is to apply successive layers such as uncured sheet rubber.

However, manual methods are often impractical due to high manufacturing costs; the use of fluid polymeric materials and automated procedures is preferred to lower costs.

Polymeric materials that can be used to make tires according to the invention include:
Elastomers, elastoplastic materials or high modulus plastics.

The softer, low modulus layer of the tire is made from an elastomeric and/or elastoplastic material, and the harder, high modulus layer is preferably made from an elastoplastic material or high modulus plastics.

Elastomers have a main glass transition point of about -20°C or lower,
Young's modulus is 100 to 6,000 pounds per square inch (7
,03 to 421 kg/ca), and the permanently modified form is characterized by the ability to withstand elongation of 100% or more without failure.

Useful elastomers include polyurethane rubbers, natural rubbers, poly(butadiene) and various other synthetic rubbers including SBR rubbers.

The material of the polymer of elastoplastic is 3 per square inch.
,000~50,000 pounds (210°9~3515
kg/crIL).

At room temperature, these materials typically exhibit a yield point below 50 φ elongation and have a yield point of 4,000 pounds per square inch (281,2
It exhibits an ultimate tensile strength of 100 kg/cIL or higher and an ultimate elongation of 100 modulus or higher.

These materials are usually characterized as multiphase, whose glassy or crystalline domain structure can be commonly detected.

Typical materials in this group are block polymers such as styrene-butadiene-styrene triblock polymers, polyester block polymers, segmented polyurethane polymers, and ionomers.

High modulus plastic materials have a Young's modulus of 50,000 pounds per square inch (3515 kg/CI?L)
It is characterized by a yield point and/or a breaking point at an elongation of about 15 φ or more and about 15φ or less.

They will have melting transition temperatures in the main glass region above 100'C.

Suitable materials within this group include compositions from polyamides, polycarbonates, epoxy resins and polystyrenes.

The elastomeric material used in the low modulus layer of the tires of the present invention should have a main glass transition temperature of about -20°C or less and can contain groups capable of forming covalent crosslinks.

The molecular weight of the chains between covalent crosslinks is preferably about 5.000
~40,000, and preferably s,ooo~
20,000.

Generally, the polymeric materials forming the various layers of the laminated tires of the present invention should have a calculated molecular weight of at least 10,000 and a Shore A durometer hardness of at least 20, and preferably have a hardness of at least 10,000. 1,000 per square inch
Pound is 70.3 to 9/cr? L) gives a tensile strength of

The softer low modulus layer is usually at least 30φ
and preferably has an elongation of at least 5o% and a Shore A durometer hardness of at least 30 and preferably no more than 90.

The softer, low modulus layer polymeric material preferably has a weight of at least 2.000 pounds per square inch (14o,
It has a tensile strength of 6 kg 7 cal).

There is the following general relationship between Shore hardness and Young's modulus.

Shore hardness Young's modulus (B, S and 1.R,) I) (Ponve square inch) 3
0 130 (9,14kli/cI/L)5
0310 (21,79kg/cIIL) Shore hardness
Young's modulus (B, S and 1.R, H) (lb/sq. in.) 75 1340 (94,20 to 9/ff
1) It is to be understood that the Shore hardness and Young's modulus values given herein must generally be correlated with this relationship.

The cured low modulus layer of the tire is -3 per square inch
00 to 5,000 pounds (21,1 to 351.5 kg)
/CIIL) and normally 500 per square inch.
~3. OOO pounds (35,15~210.9kg/c
yyt) range.

The preferred hardness depends on the thickness of the various layers, their arrangement, the stiffness of the harder layer, and other factors.

The cured high modulus layer typically has a density of 3,000 to 3,000 per square inch at least twice that of the adjacent low modulus layer.
100,000 pounds (210,9~7030 kg/
CIIL) range, preferably about 5,00 per square inch
0 to 50,000 lbs (351,5 to 3515 kg)
/CWL).

The ratio of the Young's modulus of each hard layer to the Young's modulus of each soft layer in laminated tires can be up to 300:t, but in passenger car tires it is more often in the range of 3:1 to 20:1.

The preferred modulus of the stiffer layer will, of course, depend on a number of factors and should be selected to provide the desired combined modulus and stiffness for the composite tire.

For example, if the laminated carcass of a tire consists of 50% by weight of a high modulus polymeric material and 50% by weight of a low modulus material, then the Young's modulus is 5% for the soft layer.
00~2,000 lb/sq.
．． 6kg/cr? L) and 4,000 for hard layers
~8,000 pounds/square inch (281,2~562.4
ky/cffl).

On the other hand, if the amount of high modulus material is only 25φ of the weight
, then the Young's modulus is io,ooo~1
5,000 pounds/square inch (703-1055 kg/
i) or as late as 20,000 pounds per square inch (14
06 kg/cri).

Generally, the total weight of the low modulus layers of a laminated tire carcass should be at least the same as the total weight of the high modulus layers, as illustrated in the accompanying drawings, and the low modulus layers should be applied to the inner and outer surfaces of the laminate, especially the sidewalls. It is desirable to provide it on the outer surface of the section.

The number of layers may be limited to reduce manufacturing costs; however, it is preferred to use at least 7 layers and more preferred to use at least 9 layers.

The number of layers is from 0.001 inch to 0.1 inch (0,0254 to 2
．． The thickness of each layer can vary from 5 to 1,000, which can be up to 54 mm).

The number of layers is preferably from 0.005 inch to 0.05 inch thick (
7 to 7 in layers ranging from 0,127 to 1,27
The range is 100.

The thickness of each layer is preferably uniform or approximately uniform, and each layer is preferably circumferentially continuous and without holes, although this is not required.

The layers are deformed during tire manufacturing, such as during tire formation, after the laminate is formed and before it is fully cured.

By varying the number of layers, their thickness, the arrangement of the layers and the hardness of the polymer used, it is possible to make an infinite number of different laminated tires according to the invention.

A simpler arrangement is generally preferred having each low modulus layer of the same hardness and each high modulus layer of the same hardness.

It is desirable that all layers be made from a generally similar polymer (ie, polyurethane) to improve adhesion between the layers.

However, it will be appreciated that the adhesion problem may be solved by the use of adhesives or perforations in the layers, or by various other means.

All high modulus layers have an elongation at yield of approximately 5 to 10 degrees and 5,000 to 20,000 pounds per square inch (35
1,5 to 1406 k19/a), and all low modulus layers have an elongation of at least 50% and
0-2,000 pounds/square inch (35,15-140.
Good results can be obtained when made from the same elastomeric material with a Young's modulus of 6 kg/a).

The tensile strength of the high modulus layer is at least 2,000 pounds per square inch (140,6 kg/ffl) and preferably at least 3,000 pounds per square inch (21o, 9k
g/Cl7L).

In a special laminate of the type illustrated in Figure 3, the layer thickness is 30.
0~i, ooo pound/square inch (21,09~70.3
1g7= ), layer M has a Young's modulus of 1,000 to 3,0
00 pounds/square inch (70.3~210.9 kg/cI
? L) and the layer H has a Young's modulus of 10,000 to 50
,000 pounds/square inch (703-3515 kg/cI
? It may have a Young's modulus of L).

The laminated tires of the present invention can be made in a number of different ways, from curable rubber or plastic sheets, or from flowable polymeric materials such as by centrifugal casting or extrusion.

The preferred method requires a flowable, curable polymeric material with a viscosity at the processing temperature that allows the material to flow under its own weight in a reasonable period of time.

The material of the low modulus layer should be one that cures in a reasonable amount of time and preferably provides a tensile strength of at least 1.000 pounds per square inch.

Polymeric materials suitable for use in the present invention are fluid polymers such as polyurethane, which can be rapidly exfoliated and
and can be easily processed with automated equipment.

The viscosity of the polymeric material can be adjusted by the use of solvents or plasticizers, by the use of heat, by the proper selection of curing agents, by varying the curing temperature, or by other means.

A number of different polymers can be used, as described in more detail below.

In the practice of the present invention, it is preferred to form the tire laminate by spraying or otherwise applying a curable fluid polymeric material onto the inside of a tire mold.

This can be done with or without a doctor blade to shape the layers.

FIG. 6 illustrates, in partial schematic form, one type of mold that may be used to make laminated tires.

It will be appreciated that this type is illustrated for purposes of explanation and not limitation, and that numerous other types of types may be used.

As shown herein, the mold generally designated 20 is derived from the left half mold 22L and the right half mold 22R.

The mold halves are attached to flat circular holding plates 24L and 24R, which are attached to support blocks 26L and 26R, respectively.

This arrangement allows the mold half, plate and support block assembly to rotate freely about the hollow shaft 30 on the ball bearings 2B.

A pair of spray tubes 32 and 34 are positioned within shaft 30 for delivering fluid polymer to the mold.

Polymer is discharged from spray nozzles at the ends of tubes 32 and 34 onto the interior surface of the mold space.

The end of the tube is held securely in place by an annular support 36 mounted on the shaft 30.

Ball bearings 38 are provided at opposite ends of support 36 around its periphery.

Rotatable support is provided for the mold halves 22L and 22R so that they can rotate freely about the axis.

The shaft 30 and support 36 may be stationary or, if desired, may be rotatably mounted.

As illustrated here, the inner surface of the mold defined by the combination of mold halves 22L and 22R indicates that a pneumatic tire, including both the tread and sidewalls, is made entirely within the mold 20. It looks like you'll get it.

However, it will be appreciated that the mold is shaped and used to form a laminated carcass section and the tread section is attached to it after the carcass is removed from the mold.

In such cases, it will be appreciated that a variety of techniques may be used to attach the tread portion and reinforcing belts may be provided under the tread if desired.

In the mold shown in FIG. 6, a spray nozzle or nozzles directs a spray of fluid polymer to the radius of the mold, as illustrated by the dashed lines radiating from the end of tube 34 in FIG. It is designed to deliver to the outside surface (tread) of the direction and also to the inside sidewall surface.

In other words, the spray nozzles deliver the fluid polymer in such a manner as to provide a layer of substantially uniform thickness over the entire interior surface of the mold.

In forming tires according to the invention, it is usually preferred to provide alternating layers of low modulus and high modulus polymeric materials.

In the model 20 shown here, two spray tubes 32 and 34 are provided for two different polymeric materials.

If three different polymeric materials are used, then three spray nozzles may be provided.

High modulus polymer is fed through spray tube 34 while flow through tube 32 is interrupted, and low modulus polymer is fed through spray tube 32 while flow through tube 34 is interrupted. It is intended to be given.

By feeding the polymer alternately through different tubes, alternate layers are formed on the tire.

Assuming that mold 20 is not stopped periodically but rather is rotated continuously, spraying from one of spray tubes 32 or 34 over one or more revolutions of the mold relative to the spray nozzle may cause A layer of coalescent material is formed on the inner surface of the mold.

Other layers are then formed in the same manner during one or more revolutions by spraying the polymeric material from another spray tube.

It will be appreciated that centrifugal force based on the rotation of the mold can assist in shaping the layers, so that various centrifugal casting methods can be used to ensure proper casting of the mold.

However, it is desirable to provide a curable polymeric material that cures quickly enough so that one layer retains its shape while the first layer is applied.

It is also desirable that the rapidly curing material ensure the formation of a layer of substantially uniform thickness that can retain its shape during rotation of the mold.

The sequence of operations depends, in part, on the rate of cure and the rate at which the fluid polymeric material can be fed.

For example, the mold is rotated slowly and the polymeric material is delivered from one spray tube at a rate such that the desired peripheral layer is formed in one revolution of the mold.

The parent process can also be modified to require several revolutions of the mold between formations of layers.

If so, it may be necessary to continue rotating the mold one or more revolutions after forming the peripheral layer to allow substantial curing before spraying the next layer.

If the curing rate is fast enough, it may be possible to begin spraying the subsequent layer within half a revolution after the previous layer has been applied.

The expression "partially cured" as used herein indicates that the material has been sufficiently stiffened or cured to retain adequate dimensional stability so that subsequent layers can be applied.

This expression does not necessarily require true hardening of the material.

It is noted that a variety of fluid polymeric materials may be used using a mold of the general type illustrated in FIG. It will be appreciated that other techniques for moving the fluid material on the mold surface can be used to make adjustments.

It will be appreciated that a variety of fluid polymers can be used to carry out the method of the present invention, including heptamers, melts, prepolymers, and solutions.

Fluid polymeric materials should be liquid during processing and should have a viscosity at the processing temperature such that they will flow under their own weight in a reasonable time.

One of the preferred polymers used in the practice of this invention is polyurethane.

Such polymers have a molecular weight of at least 1.000 with 0.95 to 1.2 equivalents of organic polyisocyanate having 2 to 3 functional inocyanate groups and react with unsocyanate (-Neo) groups. It is generally prepared by reaction with one equivalent of a specific compound containing an active hydrogen atom.

Organic chain extenders containing hydroxyl groups, amino groups, carboxyl groups or other groups with active hydrogen atoms that react with isocyanate groups are often used.

-NCO! Examples of organic compounds having active hydrogen atoms that react with hydroxyl end groups include polyesters, polyesteramides, polyvalent polyalkylene ethers, polyvalent polythioethers, and polyacetals having hydroxyl terminal groups.

The organic polyisocyanates used in the process of the present invention to produce polyurethanes are disclosed in U.S. Pat.
aliphatic, aromatic, cycloaliphatic, as disclosed in
and heterocyclic types, and preferably contain at least 8 carbon atoms.

Excellent results were obtained using toluene diisocyanate (TDI), 4
．． 4'-diphenyl-methane diisocyanate (MDI)
) or other aromatic diisocyanates such as diphenylalkane diisocyanates.

For example, organic diisocyanates include 2,4- and 2.6-
-Toluene diisocyanate 80:20 or 65:35
It can be a formulation of

Diisocyanates suitable for use in the practice of this invention preferably have from 8 to 20 carbons and are disclosed in U.S. Pat.
, 701, 374.

Suitable diisocyanates are 3,3'-dimethyl-4,
4'-diphenylmethane diisocyanate, 3,3'-
Dimethyl-4,4'-biphenyl diisocyanate, 3
, 3'-dimethoxy-4,4'-biphenyl diisocyanate and the like.

Mixtures of the various diisocyanates mentioned above can also be used.

Polyurethanes of desired molecular weight suitable for use in the present invention can be made by a variety of methods and are suitable in a number of different types.

However, it is preferred to use difunctional reactants which produce flexible linear polymers.

For example, a polyhydric alcohol or hydroxyl-terminated polyester or polyester may be reacted with an organic diisocyanate to have either essentially all hydroxyl end groups or all isocyanate end groups.
A liquid prepolymer having a molecular weight of 0.000 is produced and the prepolymer can then be cured with diamines, diols or diisocyanates depending on the terminal or trailing groups within the prepolymer.

Preferred polyurethanes have a molecular weight of 800 to 20,000.
capping the hydroxyl groups of polyalkylene glycol with diisocyanate to produce a prepolymer;
The prepolymer is then chain-extended and cured with a diamine or diol curing agent such as MOCA or alkylene glycol.

Hydroxyl-terminated polyesters that can be used to form polyurethanes are the reaction products of polyhydric carboxylic acids and polyhydric alcohols as described in the aforementioned US Pat. No. 3,208,500.

For example, the alcohol can be ethylene glycol or propylene glycol.

Organic compounds containing active hydrogen for reacting with isocyanate groups can also be polyvalent polythioethers or polyesteramides as defined in the aforementioned patent 3,208,500, but more preferably It is a polyvalent polyalkylene ether.

For example, ethers are condensation products of alkylene oxides and glycols such as ethylene glycol, propylene glycol, butylene glycol, and the like.

Any suitable alkylene oxide condensate may also be used, such as those of ethylene oxide, propylene oxide, butylene oxide, amylene oxide, styrene oxide, and mixtures thereof.

In producing the liquid prepolymers used in the process of the invention, an organic diisocyanate (preferably MDI or TD) is used.
IX - Polyalkylene glycols with a molecular weight ranging from 1800 to 20,000, especially poly(ethylene glycol) having alkylene groups of 2 to 10 carbon atoms.
, poly(propylene glycol), poly(trimethylene glycol), poly(tetramethylene glycol), poly(hexamethylene glycol), high molecular weight copolymers of such glycols, and mixtures of the above poly(alkylene glycols). It is preferable to react with poly(alkylene glycols) such as .

Preferred prepolymers have terminal incyanate groups;
and can be cured with various diamines.

The diamines preferably have 2 bonded to two amine groups.
Containing organic central radicals of ~20 carbon atoms, such as ethylene diamine, tetramethylene diamine, hexamethylene diamine, p-phenylene diamine, methylene diamine, etc.
Bis-2-chloroaniline (MOCA'"), 4,4'
-methylene-bis-aniline, 3,3'-dichloro-4
,4'-diaminodiphenylmethane,bendecine,3,
They are 3'-dimethylbendecine, 3,3'-dimethoxybenzidine, 3'3'-dichlorobendecine, 4,4'-diaminodiphenylmethane, and cumendiamine.

In these polyurethane rubbers, the chains of the cured polymer consist of repeating bonds (-P-0-CO-NH-R, -N
H-Co-NH-R2-NH-CO-NH-R1-NH
-CO-O), where P represents a high molecular weight poly(alkylene ether) chain, R1 is an organic radical of a diisocyanate, and R2 is an organic central radical of a diamine.

Polymers of this type with suitable molecular weights, when used to provide the high and low modulus layers of tire laminates,
Excellent results can be obtained when implementing the present invention.

The hardness and modulus of these polyurethane polymers are
For example, it can be enhanced by increasing the isocyanate and glycol or diamine content of this system.

The type of polyurethane selected for use in making tires according to the invention depends on the type of manufacturing process used.

Polyurethanes that are best suited for spraying methods may not be best suited for film extrusion or some other methods.

Fluid polyurethane rubbers are currently commercially available and can be used in the practice of this invention.

Good results have been obtained, for example, with adiprene L-1 manufactured by I. I. DuPont de Nemours and Company.
00 prepolymer (4,1 yen, NC0), adiprene L
-167 prepolymer (6,3% NC0) and adiprene L-315 prepolymer (9,5% NC0).

These liquid prepolymers include MOCA,
CAYTUR7 or CAYTUR21 (
It can be cured using common diamines such as 4°4'-methylene-bis-aniline) in an equivalent ratio of diamine to prepolymer of about 0.95 to about 1.10.

CAYTUR7 is a eutectic mixture of m-phenylene and cumendiamine.

Polyurethane prepolymers such as Adiprene-L prepolymers are made from polyalkylene glycols or polyols such as TDI and poly(tetramethylene ether diol), and similar prepolymers are
It can be made by substituting MDI for DI or by using a somewhat different polyol.

A variety of poly(alkylene glycols) and poly(alkylene ether) polyols can be used.

Both diols and triols, and prepolymers, can have either terminal -0H groups or terminal -NCO groups.

(The latter is preferred.

) The polymeric material used in the tires of the present invention may also be a polyamide plastic such as nylon 66, nylon 610 or nylon 6.

A variety of long chain synthetic polymeric amides having repeating amide groups as an integral part of the main polymer can be used.

For example, those prepared by condensation of a diamine and a dibasic acid, those obtained by condensation of a polyhydric carboxylic acid with a polyamine, or those obtained by polycondensation of caprolactam.

Various triamines can also be used, such as diethylenetriamine, but it is preferred to use diamines.

Suitable diamines include ethylene diamine, diethylene diamine, pentamethylene diamine, hexamethylene diamine, phenylene diamine, etc., or mixtures thereof.

Various polybasic acids range from succinic acid to sebacic acid and include, for example, succinic acid, aconic acid, adipic acid,
These include malic acid, itaconic acid, fumaric acid, etc., and are used in the production of polyamides.

Polyamides suitable for use in rubber tires that can be used in the practice of this invention are disclosed in U.S. Pat.
500 and is incorporated herein by reference.

Preferred polyamides are those formed from diamines and dibasic acids, such as the reaction products of hexamethylene diamine or similar diamines with adipic or sebacic acid.

Although there are many different types of polymers that can be used in the practice of this invention, the most promising polymers are polyurethanes, as generally discussed in the aforementioned U.S. Pat. No. 3,208,500. and polyamide or nylon.

At present, the most practical polymers appear to be polyurethanes, particularly polyether urethanes and polyester urethanes.

One advantage of polyurethane is that it can be obtained in liquid form with a viscosity suitable for spraying or spreading.

It can also be used in both high modulus and low modulus layers, thus reducing adhesion problems.

It is also possible to blend polyurethanes of different molecular weights to obtain the desired physical properties.

For example, the laminated tire of the present invention uses adiprene L-42 (molecular weight about 3,000) for the low modulus layer and adiprene L-167 (molecular weight about 1.3
30) can be used.

A high modulus layer could also be made using a blend of 60 parts by weight of Adiprene L-167 and 40 parts by weight of Adiprene L-315 (molecular weight about 900).

The curing agent may be MOCA, CAYTUR 21 or other suitable diamine, and the plasticizer, if desired, may be dioctyl phthalate or the like.

The curing agent was able to provide adequate fast curing to minimize the time delay after each layer was applied before back-up layers were applied.

Polyurethane polymers can also be modified in a variety of ways to produce desired physical properties.

For example, adiprene L-167, a prepolymer with a Pruckfield viscosity of about 5,000 to about 7,000 centipoise at 30°C and about 250 to about 350 centipoise at 100°C, is suitable for providing a rubber layer of the desired type. It can be cured with appropriate proportions of 1.4-butanediol and trimethylolpropane.

A curable polyurethane composition is made, for example, by mixing 160 parts by weight of adiprene L-167 with about 9 parts of 1,4-butanediol, about 1,6 parts of trimethylolpropane, and a small amount of dioctyl phthalate. Can be done.

The laminated tires of the present invention are preferably constructed such that the tear strength (split sample method) of the laminates is from 50 to at least 400 pounds per inch so that the low modulus layer is at least 1.0 pounds per inch.
Tensile strength of 00 lb/sq., Shore A durometer hardness in the range of about 30 to 90, and at least 50%
(more preferably at least 100φ).

The curable polymers used in the practice of this invention need not be fluid, although fluid polymers are preferred as they facilitate fabrication.

The viscosity of the fluid polymer is, for example, 1,000 to 50,0
00 centipoise and should be less than 100,000 centipoise at 30°C.

Viscosity can sometimes be adjusted by adding a plasticizer, such as dioctyl phthalate, in a substantial amount up to 10 or 20 parts per 1'OO parts by weight of polymer.

In such cases, a solvent may be used with the polymer to provide the desired fluidity.

The choice of solvent depends on the type of polymer and the type of curing system.

Various solvents that may be used include ethyl acetate, acetone, toluene, methyl ethyl ketone, xylene, beta-ethoxyethyl acetate, and the like.

These are preferably relatively pure and moisture-free.

Although the pneumatic tire laminates described above use substantially different polymer formulations in the low modulus and high modulus layers, the present invention also provides that similar formulations are used in all layers and in any direction (circumferentially). It will be appreciated that an improved laminate having improved bending crack resistance is contemplated where the tensile modulus (such as directional or radial) differs substantially within adjacent layers. .

In accordance with the present invention, differences in tensile modulus can be imparted between adjacent layers (e.g., FIG. 2) H and L when the same polymer is used in both layers as a result of different molecular orientations in the adjacent layers. .

As used herein, the term "tensile modulus" refers to the poundage per pound that must be exerted on a sample to stretch it to a stated degree of elongation, such as 10%, 100%, or 200%. Says the stress of square inches.

In a laminated tire constructed in accordance with the present invention (eg, as in FIG. 2), each layer has a modulus of 10% in one direction, which is at least about twice that of the next adjacent layer in that direction.
% modulus.

For example, the desired difference in tensile modulus between layers H in the various types of FIGS. 2 through 5 can be achieved by molecular orientation within the different layers or by the use of different polymers or both. This can be achieved by

One advantage of using the same or similar polymers in adjacent layers is that good adhesion is easily achieved.

As used herein, the term "parts" means parts by weight and the term "hexapolymer" includes mono-polymers or copolymers unless the context indicates otherwise.

The term "fluid" as applied to polymeric materials indicates that the material has a viscosity that allows it to flow during processing.

The viscosity is, for example, 100-10,000 centipoise at 30°C and should not exceed 100,000 centipoise at that temperature.

The following examples are intended to illustrate the essence of the invention, and are not intended to limit the invention.

EXAMPLE This example is included to illustrate the greatly improved ability of tires made in accordance with the present invention to resist the propagation of cuts or the formation of cracks.

To exemplify this ability, laminated and homogeneous samples were subjected to the De Mattia flex test, with each laminate sample and a homogeneous sample made from a formulation of the same proportions of materials in each laminate sample and in the individual laminate sample. Comparisons were made between quality samples.

Each sample is 1 inch wide, ± inch thick and 6 inches long.

These were press hardened at 2500F (121C) for 2 hours and after the blades were heated in an oven for an additional 2 hours at 176F (80C).

Each sample had a 0.1 inch (0.254 m) artificial wound extending across the 1 inch wide surface and perpendicular to the 1 inch wide surface.

Fatigue testing was performed on a DeMattia bending machine, which bends the sample (333 cycles/L=10 and at room temperature) to propagate the inflicted scratches laterally across the width of the sample.

Two different material formulations were used for this experiment, which will be referred to as 100'' and 167'' (parts by weight) as follows: and the De Mattia test is 0
．． 1 inch (0,254 CrrL) wound 0.5 inch (1,27
crfL) was used to determine the number of cycles required to reach

The number in parentheses below each pound per square inch reading represents 106 pascals.

Besides, other physical properties were measured as follows.

*Note (1) and (2) are liquid prepolymers as mentioned above, (3) is a liquid silicone mold release and emulsifier, Dow Corning, and (4) is a methylene dianiline/sodium chloride complex in dioctyl phthalate. 50 coefficient dispersion screening, DuPont.

Formulations "100'" and 167" were then used to make samples containing both materials.

In the case of formulations, the ratio stated in the expression is "t o o
For the laminate** reported in Table 1, the ratio of ``100'' to ``167'' is greater than that of ``167'' because both outer layers are ``100''. There are many.

Referring to the representation, the second column contains two ", 10"
It has the heading "3-layer" indicating a laminated sample consisting of an outer layer of 0" and a center layer of 167".

The next column 2:1 is 2 parts by weight of 100" and 1 part by weight"
A homogeneous sample made from a 167" formulation is shown.

The subsequent columns show laminated and homogeneous samples of different proportions.

For example, as shown in the last column, a 9 single layer laminate sample can be compared to a homogeneous sample made from a 5:4 formulation.

The above data demonstrate that a significant increase in fatigue life such as 400-500φ can be achieved with laminated samples while still retaining physical properties suitable for the conditions to be expected in pneumatic tires. It's proven.

Although the data for tensile strength and elongation are somewhat scattered, this behavior does not diminish the fact that this occurs at strains far beyond those continuous in end use, and that significant improvements are observed in fatigue life. .

The somewhat diffuse behavior in tensile strength and elongation at break in these samples is related to flaws in the samples that affect these physical properties rather than bending behavior.

It will be understood that, subject to the provisions of the state of the invention, changes and modifications may be made to the particular methods and articles disclosed herein without departing from the spirit of the invention.

[Brief explanation of drawings]

FIG. 1 is a fragmentary perspective view of a pneumatic tire of the type made according to the invention on a scale; FIG. 2 is a fragmentary cross-sectional view of the laminated tire of FIG. 1 showing a portion of the tire sidewall; ,4
and FIG. 5 is a fragmentary view similar to FIG. 2 showing alternate embodiments of a laminated tire according to the invention, and FIG. FIG. 2 is a partial, schematic cross-sectional view; 10...Pneumatic tire, 12...Tread portion, 14...Side wall portion, 20...
Type, 22L... Left half type, 22R...
Right half type, 24L...Press plate, 24R...
...Press plate, 26L...Support block, 26R
...Support flock, 28...Pole bearing, 30...Hollow shaft, 32...
Tube, 34... Tube, 36... Annular support material.

Claims (1)

Claims: 1. Applying a successive layer of a first polymeric material in an annular shape, then partially curing the material, and then applying a second layer to the partially cured layer. applying successive layers of coalescent material;
The second material is then partially cured, and the application and partial curing of the polymeric material is repeated sequentially to form a curable laminate of at least seven layers, while the laminate has a generally toroidal shape. In a method for manufacturing a pneumatic tire having a laminated carcass of properties with improved resistance to flex cracking, which comprises heat curing the laminate, said continuous layer has a viscosity of less than ioo, ooo centipoise at 30'C. using two different liquid polymers with each layer having at least two
one series of the layers has a Shore A durometer hardness of about 100 to about 500 per square inch.
0 pounds (7,03kg/crtl~351.5yu/c
rtl), the other series of layers having a tensile modulus of at least the tensile modulus of the low modulus layer at 10 percent elongation in either direction. An improved method comprising a plurality of high modulus layers alternating with low modulus layers as described above, having a tensile modulus in either direction that is twice as high.