AU6777094A

AU6777094A - Dimensionally stable reinforced thermoplastic pvc articles

Info

Publication number: AU6777094A
Application number: AU67770/94A
Authority: AU
Inventors: Bryan Michael Kazmer
Original assignee: Geon Co
Current assignee: Geon Co
Priority date: 1993-05-03
Filing date: 1994-04-28
Publication date: 1994-11-21
Also published as: EP0696963A1; WO1994025272A1; BR9406364A; KR960702384A; JPH08509673A; CA2161330A1

Description

DIMENSIONALITY STABLE REINFORCED THERMOPLASTIC

PVC ARTICLES

Field of The Invention

This invention relates to composite articles containing flexible fiber reinforced polyvinyl chloride.

Background of the Art

European patent publication 411 429 published 2-6-91 discloses articles made from high molecular weight polyvinyl chloride, plasticizer, and reinforcement material. The reinforcement material is selected from particulate or fibrous materials. The polyvinyl chloride has a molecular weight in terms of inherent viscosity above 1.0 preferably 1.4 to 1.7. This material is designed to sustain low continuous load and exhibit little or no deflection at high temperatures. Particulate reinforcement is not distinguished from fiber reinforcement.

U.S. patent no. 3,892,692 discloses ethylene vinyl chloride copolymers which are plasticized and exhibit improved plasticizer permanence. The copolymers contain a modulus index of less than 3000 psi as compared with rigid polyvinyl chloride having a modulus of 300,000 psi. Any type of reinforcing fillers can be used among those suggested are clay, iron oxide, calcium carbonate, asbestos, glass, rayon, and mineral wool. This patent does not acknowledge that non-fibrous reinforcement behaves differently with respect to dimensional stability when combined in a plasticized, flexible matrix, as compared to fibrous reinforcement.

Plasticized polyvinyl chloride has been exploited as a useful tough, weatherable material. US-A-3 084 078 is a general disclosure of phthalate ester, a widely used plasticizer. US-A-2 535 643 discloses a class of plasticizers and any usual commercial PVC (see column 3, lines 20-22). US-A-3 796 681 is directed to plastisols.

EP-A-0 057 470 broadly shows non-reinforced plasticized PVC. The fiber reinforcing of rigid thermoplastics has been commercially exploited in structural uses to provide for rigidity (modulus enhancement) beyond that obtainable from the rigid thermoplastic matrix alone. Chopped glass fibers having a diameter from about 10 microns to about 25 microns have been commercially developed specifically for this purpose. The addition of glass fibers to a rigid thermoplastic matrix resin reduces the coefficient of linear thermal expansion (CLTE) of the composite. There are practical upper limits on the amount of glass fiber content usable with PVC, hence limits on the extent of reduction in CLTE using glass fibers alone with PVC.

There has been observed an inverse relationship between CLTE of the fiber reinforced composite and the tensile modulus of the thermoplastic matrix of the composite. That is, when one compares the coefficient of linear thermal expansion of two different glass fiber reinforced thermoplastics, the matrix which has the lower modulus will exhibit a relatively higher CLTE for the reinforced composite.

In some end use applications for non-structural thermoplastic polymers, the high tensile or flexural modulus is not needed, however due to poor dimensional stability, the designer often is of the belief that high modulus is needed to prevent distortions in the article. The present invention is contrasted with conventional approaches suggesting high structural strength. The composites of the present invention contain a non- structural component which has low modulus and strength however, this component possesses an improved degree of dimensional stability, thereby avoiding the build-up of load stress under changing environmental conditions of exterior applications. The high dimensional stability of the non-structural component in this invention, over a broad temperature range, is sufficient to enable close tolerance fit with the structural component without distortion of the non-structural component. When fibers are present in a viscous thermoplastic melt undergoes, during processing there is fiber orientation along shear force lines, this may result in non-uniform CLTE throughout the article, possibly resulting in later distortion. It is desirable to achieve a less random orientation of fiber reinforcement in the thermoplastic matrix in order to obtain the lowest CLTE in one direction, especially for elongated articles having high aspect ratio. Summary of the Invention

In accordance with the invention there is provided a composite of a reinforced, plasticized polyvinyl halide composition (A) integrally bonded to a structural member (B) by mechanical or adhesive fastening means. The structural component (A) is selected from the group consisting of metal sheet, shaped metal articles, rigid thermoplastic, and rigid thermoset articles. The composite optionally and preferably further comprises an appearance (C) layer overlying (A) on the surface not contacting (B). The appearance layer (C) can completely surround (A) or cover only the show side with a small portion extending around the edge of the show side so as to provide a area for trimming (C) which is not seen. Preferably (C) comprises a thermoplastic compound such as non-reinforced, pigmented plasticized polyvinyl halide composition, decorative paint and the like. The structural component (B) is generally selected from the group consisting of a rigid molded, stamped or shaped metal article such as a steel, aluminum or thermoset polymer article, a metal door, a metal door casing, a window pane, and a metal window casing, to name a few examples. The structural component

(B) can be coated or non-coated for example in a painted automotive body panel, a RIM molded thermoset polymeric article in the shape of a bumper. Component (A) is most advantageously formed in the shape of an auto body side molding, weather seal profile, cove trim piece for pools and auto bumper fascia, to name a few examples. Component (A) is a non structural component and does not have the capability to sustain stress loading. Structural component (B) must be joined with (A).

Component (A) comprises: a PVC miscible plasticizer, polyvinyl chloride homopolymer resin, and fibers. The polyvinyl chloride exhibits a preferred intrinsic viscosity measured according to ASTM D1243 of from 0.4 to 0.9. Molecular weights in terms of inherent viscosity of between 0.5 and 0.7 exhibit the best combination of melt strength and flowability. The preferred (A) component has poorer sag strength than materials taught in EP 411 429, and is not as useful for structural strength. Plasticizer is present at a level of from about 15 weight parts to about 150 weight parts per 100 weight parts polyvinyl halide resin in (A). Plasticizer is preferably present in (A) at from 20 weight parts to 55 weight parts per 100 weight parts polyvinyl halide in (A). Fibrous reinforcing material can be selected from the group consisting of chopped glass fibers and polymeric fibers, such as aramid, polyamide, polymethacrylate, fibrous derivatives of cellulose non-glass fibers are usable but less preferred for economic and technical reasons. In addition to plasticizer component (A) can further contain a flexible polymeric material, for example, EVA, SBR, NBR, MBS, acrylic rubber, ABS, urethane, copolyester, styrenic block rubbers, any of which may or may not be completely miscible with PVC.

Component (A) exhibits among the lowest coefficient of linear thermal expansion per ASTM D696 of any material useful for molding of shaped plastics when sufficient amounts of plasticizer are used. Generally at least 15 weight parts per 100 weight parts

PVC is required in (A). The plasticized PVC polymer will have a PVC phase having glass transition temperature of less than 50°C. The plasticized PVC matrix has reduced tensile modulus measured per ASTM D638 compared with rigid fiber reinforced materials. However, because component (A) is joined with a structural component (B), the strength and rigidity are not required in (A). The plasticized, reinforced material exhibits significantly better dimensional stability as shown by CLTE and overcomes the lack of structural strength.

The amount of glass fibers generally can range from 3% to 50% by weight fiber reinforcement material. Dimensionally stability is further improved along with a balance of good properties when the glass fibers are present at from 10 to 30 percent by weight. The preferred chopped glass fibers have a diameter of from about 8 to 25 microns and length of from 1 to 25 mm prior to combining with the thermoplastic. Upon incorporation into PVC, the glass fibers are broken leaving a variety of fiber lengths. Preferred glass fibers dimensions and 10-13μm by 3-6 mm. Optional particulate or platelet reinforcement material can also be combined with or can displace a quantity of fiber reinforcement and results in a non-structural material having CLTE of 4x10^"5 °K^"' or less and a good combination of physical properties. The articles are shaped according to the forming method employed and exhibit a tensile modulus below that of reinforced rigid thermoplastic PVC, that is a modulus of from about 0.1 Gpa to about 0.5 Gpa. The coefficient of linear thermal expansion for the preferred embodiments, per ASTM D696, is measured from -30°C to +30 °C and is found to preferredly lie in a range of from about O.lxlO^"5 °K^"' to 4xl0^"5 °K^"', more preferably from l.OxlO^"5 °K^"' to 2.9xl0^"5 °K^"', and still more preferably from l.OxlO^"5 °K^'' to 2.0xl0^"5 °K-\

In accordance with the invention there is provided a composite comprising an extruded non-structural component (A) as above which exhibits a coefficient of linear thermal expansion of from O.lxlO^"5 °K^"' to 4xl0^"5 K^"1. (A) is prepared by subjecting the (A) compound to an extrusion process whereby a shaped profile is formed which conforms to the cross-section of the extruder die. The preferred extruded non-structural articles are elongated and have an aspect ratio of length to width of at least 2, preferably 4, more preferably about 6 to 50 or more. The fiber orientation provides an improved CLTE in the axial direction, and the magnitude of lineal expansion is desirably very low.

In accordance with the invention there is provided a composite article containing non- structural component (A) formed by injection molding process. The article has excellent dimensional stability. Using the method of injection molding, the compound is formulated for high melt flowability and the molten material containing glass fibers adequately flows to fill the entire void in the mold. The non-structural component (A) exhibits excellent dimensional stability and can be used in contact with rigid structural articles with tight size tolerance, without causing a distortion in the weaker component

(A).

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a log-log plot of tensile modulus (GPa) on the x-axis versus coefficient of linear thermal expansion ( X 10^"5 °K^"' ) (CLTE) for a variety of materials. The triangular data points include metals, and rigid, fiber reinforced thermoplastics, as well as rigid non-reinforced thermoplastics. The circular data points are measurements made from examples of the method of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The triangular data points in Figure 1 illustrate a plot of CLTE versus tensile modulus for a variety of materials. The symbols used represent the following:

CLTE (X1Q-⁵ °K)

• P-PVC - plasticized particulate reinforced polyvinyl chloride 36

• LDPE - low density non-reinforced polyethylene 18

• HDPE - high density non-reinforced polyethylene 12

• PP - non-reinforced polypropylene 11.2

• PS - non-reinforced polystyrene 7.2

• PC - non-reinforced polycarbonate 7.0

• u-PVC - particulate reinforced, non-plasticized rigid polyvinyl chloride 6.3

• magnesium 2.6

• aluminum 1.8

• brass 1.8

• copper 1.7

• stainless steel 1.6

• carbon steel 1.2

The table above illustrates that non-reinforced thermoplastic polymers or particulate reinforced thermoplastic exhibit higher coefficient of linear thermal expansion and relatively lower tensile modulus compared to a like polymer containing glass reinforcement. None of the thermoplastic materials represented by triangles, whether fiber reinforced or not, exhibit a CLTE as close to metals aluminum (Al). magnesium (Mg), brass, Copper (Cu), 316 stainless steel (SS) and carbon steel (steel). They vary by at least a factor of two, and in many instances by a factor of 7 or more. As the graph depicts, comparing PP to GFPP, as expected, glass fibers increase the tensile modulus and reduce CLTE. With respect to PVC and GFPVC, the same effect is noted.

The trend in the triangular data points of figure 1 suggests that the tensile modulus of the matrix material and the CLTE of fiber reinforced versions are inversely proportional. The lower CLTE of examples A- K for glass reinforced, plasticized PVC does not follow the observed trend in that with a higher proportion of plasticizer there is the expected reduction in modulus, however CLTE is decreased. Reduction of CLTE to this extent is important since these levels of CLTE are very near or can be made equal to that of dissimilar structural materials. Because the non-structural component (A) has no structural strength and cannot sustain load stress, the material would easily distort, however due to the excellent dimensional stability, no distortion is observed. Also there is no distortion over a wide temperature range making these articles highly desired for exterior decorative trim for automobiles. The composite containing non-structural component (A) can have a close match of the CLTE of the structural component (B) to which it is attached. As explained previously, non- structural uses are uses where an article does not bear sustained load stress. Sufficient internal stresses would lead to permanent distortion or creep for the non-structural component (A) if it were not for the excellent dimensional stability. In many applications the non-structural component (A) can be tightly attached to the structural component (B) and maintain adherence over a wide temperature range and under prolonged thermal cycling without weakening or compromising the attachment means.

Conventional methods for attaching the non-structural component (A) to structural component (B) can be used. These include the use of adhesives such as acrylic pressure sensitive adhesives, adhesive coated foam tapes, urethane adhesives, epoxy adhesives, and hot melt adhesives all of which are in commercial use. Mechanical fasteners or ri vetting can be used. Thermal bonding or dielectric heating could be used also, these methods being known and available methods beyond the scope of the invention. The plasticized matrix material must exhibit a dominant PVC phase morphology. Those materials which reduce the modulus in a blend with PVC but which are immiscible with PVC are less preferred in the present invention. A combination of PVC miscible plasticizer and non-miscible polymer is however useful. Miscibility herein means that the plasticized matrix must exhibit a Tg which is lower that of a rigid matrix PVC. The matrix may also include lubricants processing aids and at least one stabilizer for PVC. Impact modifiers are not generally required but may be used.

The plotted data point for example A in figure 1 represents the measured properties obtained by combining 35 weight parts of plasticizer with polyvinyl chloride (100 wt. parts) having an inherent viscosity of 0.68. The CLTE of example A was 3.1 xlO^"5 °K^' ¹ and is lower than rigid unplasticized PVC shown in figure 1 having a CLTE of 3.2 xlO^'5 °K^''. The modulus of example A was 1.4 GPa versus 5.1 GPa for rigid, glass reinforced, unplasticized PVC.

Example B plotted in figure 1 resulted from the combination of 100 wt. parts PVC (I.V. 0.52) with 10 parts of polyacrylate processing aid and 35 parts of mixed alkyl (C₇-

Co-C_n) phthalate plasticizer, stabilizer, lubricants, and an amount of 0.25 x 13 micron glass fibers sized with aminosilane coupling agent such that the total composition contained 30% by weight of glass fibers. As figure 1 shows the modulus of example B has been reduced below that of rigid GFPVC but is higher than example A; and the CLTE is also favorably identical to the CLTE of aluminum. Aluminum can be used as a substrate for this article over a broad temperature range.

Example C represents the combination of 52 weight parts of plasticizer in a compound similar to example B, but having glass fiber content of 20% by weight. There is noted a still further reduction in CLTE versus example B due to the additional plasticizer even though the amount of glass content is 20% by weight in C versus 30% by weight in B. The modulus of C is reduced from 1.9 GPa to 0.79 GPa, yet the magnitude of tensile modulus is not of primary concern for the aforementioned uses. Example D contains a still lower CLTE than example C yet has a higher tensile modulus as C and for some uses this a more desirable combination of properties. In table 1 below are listed the weight percent glass fiber content and parts plasticizer per 100 weight parts PVC resin for the examples A-K plotted in figure 1.

TABLE 1

EXAMPLE CLTE TENSILE % GLASS WT. PARTS

(x10⁵ MODULUS CONTENT PLASTICIZER

°κ-¹) (GPa)

E 2.0 0.18 10% 74

G 1.8 0.11 10% 82

Examples E and G have a CLTE below GFPVC. As can be seen from the data above that increasing the level of plasticizer from 74 to 82 phr, at a fixed weight percent glass content causes a reduction in the coefficient of linear thermal expansion.

TABLE 2

EXAMPLE CLTE TENSILE % GLASS WT. PARTS

(x10⁵ MODULUS CONTENT PLASTICIZER

°κ-¹) (GPa)

C 2.2 0.79 20% 52

D 2.1 1.2 20% 52

H 1.8 0.50 20% 55

J 1.5 0.43 20% 82

K 1.3 0.21 20% 82

As can seen in table 2, that with 20% glass fiber content and a plasticizer content of either 52 to 82 parts per 100 parts PVC yields reduced CLTE. It can be also seen that the modulus of the composite is also reduced.

TABLE 3

EXAMPLE CLTE TENSILE % GLASS WT. PARTS

(x10⁵ MODULUS CONTENT PLASTICIZER

°K^'1) (GPa)

A 3.1 1.4 30% 35

B 2.4 1.9 30% 35

F 1.9 4.9 30% 35

I 1.7 0.81 30% 52

As table 3 shows, the plasticizer content of 35 or 52 parts per 100 parts PVC yields a 30% glass fiber reinforced PVC composite having a reduced CLTE. The above examples each contained polyvinyl chloride homopolymer having an I.V. ranging from 0.5 to 1.1, a stabilizer such as an organotin or a mixed metal soap type, such as a barium-zinc stabilizer. Preferred stabilizers are mixed metal types. The amount of thermal stabilizer used can range from 1 to 5 weight parts. There can be included other conventional additives such as processing aids, or impact modifiers, pigments or colorants, UV stabilizers and co-stabilizers known in the compounding art. Impact modifiers are not generally need because of the inherent toughness of the plasticized matrix. The articles exhibit Izod impact strength of at least 1 ft-lb per inch of notch. Preferred processing aids are polyacrylates, for example those commercially available from Rohm and Haas, Inc. under the Paraloid trademark. Most preferred processing aids are styrene-acrylonitrile copolymers. The conventional lubricant waxes, polyol esters, and fatty soaps can be used. The preferred lubricant is a silicate type, in which the resulting surface tension of the surface of a shaped article is higher than 35 dynes/cm, preferably 45 dynes/cm and most preferably from 45 to 65 dynes/cm² in order provide improved adhesion to coatings or applied films. In-mold transfer of films during formation is a preferred method of joining one side of the non-structural article to appearance films such as pigmented non-reinforced flexible PVC films. Amounts of from 2 to about 15 weight parts of lubricant can be used, with the type and amount of lubricant and stabilizer depending on factors beyond the scope of this invention.

Any of the conventional processes for making PVC polymers such as mass, suspension, solution or emulsion polymerization methods can be used. Mass and suspension polymerization methods are the preferred processes. Suspension polymers are most preferred. Porous, commercial suspension grade homopolymer PVC having an I.V. of from 0.4 to 0.85 are preferred with the more preferred PVC polymers having an I.V. of from 0.5 to 0.7. Generally the molecular weight is controlled by the polymerization temperature and/or by the use of chain transfer agents.

Although the PVC polymer can be a copolymer of vinyl chloride and terminally unsaturated comonomer(s), it is essential that the PVC resin be a rigid polymer in the unplasticized state, the preferred type of rigid polymers being a homopolymer of polyvinyl chloride. In the present invention, homopolymers maintain better physical properties in the plasticized state such as higher strength and modulus. Homopolymers or copolymers of PVC having an unplasticized modulus of elasticity of greater than 100,000 pounds per square inch per ASTM-D747 are essential for use in the present invention. Thus, flexible copolymers of PVC having a Tg in the unplasticized state of less than about 60 °C and having an unplasticized modulus for less than 100,000 p.s.i. are not suitable in the present invention. Block copolymers of homopolymer PVC may be suitable, provided there is a major predominant phase of rigid polyvinyl halide polymer which would meet the above modulus criteria. The use of flexible copolymers obviates the ability to add sufficient plasticizer to produce the CLTE lowering effect and therefore are outside the scope of the invention.

The miscible plasticizer forms a single phase, single Tg PVC matrix and is incorporated at a level of from about 5 weight parts to about 150 weight parts per 100 weight parts polyvinyl chloride resin, the amount in any embodiment depending on the modulus and CLTE desired. More preferably, plasticizer is incorporated at 20 weight parts to 65 weight parts per 100 weight parts polyvinyl chloride.

The formulations of the invention must have adequate melt flowability, usually evaluated by the spiral flow test. Spiral flow is a measure of the extent of injection melt flow under a fixed ram force input. The extent of spiral flow provides a prediction of the limitations in size and configuration of injection molding dies suitable for a given resin compound. The test employs a graduated 60-inch spiral flow mold with a standard cross section die such as a 1/8 inch by 3/16 inch rectangular cross section die used in conjunction with a Van Dorn injection molding machine. Generally, the mold temperature is set at 55°C, the injection melt pressure is a constant psi, with a constant injection time, clamp time, and mold open time, giving a constant total cycle time. A screw of specified diameter and L/D is used. Stock temperature at the nozzle is standardized also. Spiral flow is proper when the polymer is able to flow into the pattern of the mold used. The extent of spiral flow varied depending on the molecular weight of the plasticizer, the molecular weight of the polyvinyl halide polymer as well as the amount of reinforcement or other material employed. A desirable spiral flow is at least 15 inches, preferably at least 25 inches, more preferably at least 35 inches, and most preferably at least 40 inches. Contrary to conventional wisdom, it has been found that relatively low molecular weight polyvinyl chloride having an I.V. of from 0.4 to 0.85 works better in the present invention than PVC having molecular weight of 0.9 or above. When the molecular weight of polyvinyl chloride is in a range of from 0.5 to 0.7, there is exhibited the best combination of melt strength and flowability and less plasticizer is required to give the same spiral flow than with the use of high molecular weight PVC (I.V. above 1.0).

The plasticizers used in this invention are PVC miscible plasticizers to the extent that a single phase morphology results in combination with PVC. These include those taught in The Technology of Plasticizers, Sears and Darby, John Wiley and Sons, New York (1982) ch.4, incoφorated herein by reference. A suitable plasticizer may be polymeric, or monomeric such as a high Tg solid or a low Tg material but there must be a degree of miscibility such that a single phase, single Tg results from their combination. The preferred plasticizers are liquids. The amount of plasticizer employed is the minimum amount necessary to reduce the CLTE to 4 xlO^"5 °K^"' or less. Generally from at least 5 weight parts per 100 weight parts PVC (phr) is sufficient to provide a noticeable reduction in CLTE provided that the fiber content is sufficiently high, such as 10% by weight or higher. A preferred combination contains from about 20 to 85 phr plasticizer. By selecting the amount of fiber and plasticizer content the desired combinations of tensile modulus and CLTE can be obtained.

Examples of suitable polyesters with molecular weight below 10,000, especially those derived from glutaric or sebacic acid, plasticizers include the phthalates, trimellitates, epoxides, aliphatic diesters, and phosphates, including mixtures. Preferred are the phthalates trimellitates and epoxides. Examples of preferred phthalates include dioctyl phthalate, diisooctyl phthalate, diisodecylphthalate; and mixed alkyl esters such as heptyl, nonyl and undecyl phthalate. Preferred trimellitates are tri-octyl trimellitate and tri-isononyl trimellitate. The preferred epoxides include epoxidized soybean oil, and epoxidized linseed oil. As used in the present invention, a single plasticizer can be employed, as well as blends of more than one miscible plasticizer. An example of a preferred blend is a blend of 85 parts per hundred parts resin of dioctyl phthalate and 5 parts per hundred parts resin of epoxidized soybean oil. The amount of fiber reinforcement used ranges from about 3 weight percent to about 50 weight percent of the non-structural component (A). Preferably from about 6 weight percent to about 35 weight percent and more preferably from 10%. The most preferred amount of fiber reinforcement material present depends on the particular combination of properties desired as these properties can be accurately tailored to suit the requirements.

Examples of suitable fiber reinforcement materials include the various glass fiber types, such as E-glass, with or without coupling agents incoφorated thereon, either as mats, woven or non woven fibers or chopped; stainless steel shavings; polymeric fibers, such as aramid or cellulosic fibers, and combinations of more than one type of fiber. The preferred fiber reinforcing material has a diameter of greater than or equal to 8 microns, preferably 10 to 13 microns, more preferably at least 12 microns and most preferably about 13 microns, and a length of 1/8" (3 mm) or 1/4" (6 mm). Alternatively, a particular or platelet filler, or both can be included. An example is the combination of glass and mineral filler, the mineral filler being either of spherical or platelet shape. A particulate filler such as calcium carbonate and platelet reinforcement fillers such as mica or talc are exemplary types. Preferred combinations of fiber and platelet reinforcing filler are 30% fiber and 10% platelet, and 20% fiber and 20% platelet, each respectively.

The glass used in this invention can be sized or non-sized. A preferred sizing and coupling agent are disclosed in U.S. Patent 4,536,360 to Rahrig, incoφorated herein by reference which describes the use of aminosilane coupling incoφorated into a sizing containing a film former which is more basic than polyvinyl acetate. Preferred film formers are polyethers, and silylated polyazamides. Higher physical properties are seen when diaminosilane and preferred film formers are present on the glass fibers.

To prepare component (A) it is preferred to first mix plasticizer with the polyvinyl chloride resin in the initial compounding step. Fiber reinforcement material is added subsequently. As a result of the mixing, the reinforcement material, whether initially in long glass fibers or not, will be crushed and broken, and will be dispersed relatively uniformly throughout the mixture. A specific method of preparation of the composite comprises combining PVC, process aid, plasticizer, stabilizer, filler or pigment, if used, and lubricants in a Henschel mixer. The powder mixture can be fluxed under heat and shear in a Buss reciprocating extruder. Is preferred to equip the extruder with a hopper and feeding screw through which the glass fibers are added. The polymer compound and glass mixture is then sheared to uniformly disperse the glass throughout the melt. The mixture can be formed into pellets and later molded, extruded, and shaped in any conventional process for forming shaped thermoplastic articles.

The alternative would be to combine the process by directly making the melt mixture and shaping directly into the final product. No special precautions are needed to employ commercial PVC extrusion or injection molding processes.

The articles will generally be formed at temperatures high enough to induce melt flow under pressure. The temperatures and work level employed are high enough to fuse the resin particles and ensure complete plasticization of the matrix. The pressure should be high enough to extrude an article, or inject the molten composition into a mold pattern, co-extrude a composite article, or co-inject the material with another thermoplastic component such as a dissimilar plastic substrate. Typically such temperatures range from about 175°C to about 235°C, and preferably from about 180°C to about 210°C. The pressures are generally those encountered in injection molding and extrusion, co- extrusion, co-injection or laminating processes. The composition is also useful in compression molding, although this process is not favored as a commercial process.

Examples L - M

The following Examples were prepared to illustrate that both glass fibers and talc can be combined in the method at up to 40% and 50% by weight, and enable achieving the advantages of low CLTE in addition to good physical properties. The following components were combined by batch mixing in a henschel mixer, followed by force feeding to a reciprocating single screw extruder equipped with a down-stream port for incorporating glass fibers.

Example - Parts by Weight

L M

Suspension PVC (I.V. 1.0) 100 -

Suspension PVC (I.V. 0.68) - 100

Acrylic process aid 10 10

Mixed (C₇-C₉-C_n) Phthalates 50 50

Lubricants 4.4 4.4

Ba-Zn Stabilizer 3 3

Pigment 0.1 0.1

Talc* 30% 20%

* amount based of batch weight

Amounts glass were introduced through the port such that the following weight percents as obtained:

Examples- weight % L M

Chopped glass 10 20

Injection molded test plaques were prepared and the following physical properties were measured:

Examples

L M

Tensile Mod. (psi) 128,000 203,000

Tensile Strength (psi) 2,950 3,800

Tensile Elong (%) 22 5

Notched Izod (ft.-lb./in.) 1.7 1.9

CLTE xlO^"5 °K-^* (-30 to +30°C)* 2.6 1.8

Spiral Flow, (inches.)/cm. 19.3/49 31.5/34.2

* ASTM D696 From the above data for L and M it can be seen that injection molded samples exhibit a desirable combination, stress/strain, impact strength, and CLTE below that obtainable without the use of a PVC miscible plasticizer. The modulus is not indicative of rigidity, however it is understood that the method of use is for non-structural application. The desired properties are CLTE of less than 2.9X10^"4 °K^"', and impact strength of greater than 1 ft.-lb./inch of notch which is improved as compared to a rigid PVC reinforced composite absent a significant amount of conventional impact modifier.

Claims

IN THE CLAIMS:

1. A composite article comprising the combination of a non-structural component (A) and a structural component (B), component (A) comprises 100 weight parts of polyvinyl chloride as the matrix, from 10 to 150 weight parts of a plasticizer miscible with polyvinyl chloride, and from

3% by weight to 50% by weight of uniformly dispersed fibers, wherein (A) alone exhibits a dominant PVC phase having a glass transition temperature of 50°C or less, and a coefficient of linear thermal expansion per ASTM D696 of from about O.lxlO^'5 °K^"' to 4x10^"5 °K^"1*, and wherein component (B) is selected from the group consisting of metal sheet, shaped metal article, rigid shaped thermoplastic article, and rigid shaped thermoset article.

2. The composite of claim 1 further comprising the step of incoφorating a particulate or platelet reinforcement material.

3. The composite of claim 1 wherein (A) is formed as an extruded article.

4. The composite of claim 1 wherein (A) is formed by injection molding.

5. The composite of claim 3 wherein (A) has an aspect ratio of 2 or more.

6. The composite of claim 1 wherein said plasticizer in (A) is present at from 20 to 100 weight parts per 100 weight parts PVC, (A) alone exhibiting a coefficient of linear thermal expansion per ASTM D696 of from l.OxlO^"5 °K ^* to 2.9xl0^"5 °K_-^*.

7. The composite of claim 4 wherein said plasticizer in (A) is present at from 40 to

85 weight parts per 100 weight parts PVC, and (A) exhibits a coefficient of linear thermal expansion measured in any cross-sectional direction of from l.OxlO^"5 °K^"' to 2.0x10-⁵ °K-'.

8. The composite of claim 1 wherein said structural component (B) has a coefficient of linear thermal expansion of less than 3x10^"5 °K^"' .

9. The composite of claim 8 wherein said structural component is selected from the group consisting of magnesium, brass, aluminum, steel and stainless steel articles.

10. The composite of claim 9 wherein (B) and (A) are joined by mechanical fastening means for joining said articles.

11. The composite of claim 10 wherein (B) and (A) are joined by adhesive means.

12. The composite of claim 1 wherein said non-structural component (A) is shaped to form an automotive side molding and said structural article (B) is an automotive steel body panel.

13. The composite of claim 9 wherein said non-structural article (A) is a cove trim piece for a pool and said structural article (B) is a metal pool wall panel.

14. The composite of claim 9 wherein said non-structural article (A) is a weather seal profile and said structural article is selected from the group consisting of a metal door, a metal door casing, a window pane, a metal window casing, and a fiber reinforced thermoset article.

15. The composite of claim 9 wherein said non-structural article is a construction weather strip and said structural article is a rigid reinforced thermoplastic PVC construction lineal profile.

16. A process of making a composite article comprising non-structural component comprising: (a) combining

(1) polyvinyl chloride,

(2) a plasticizer which is miscible with PVC,

(3) and optional filler(s), lubricant(s), stabilizer(s), pigment(s), and impact modifiers; (b) melt mixing to form a homogenous mixture, and thereafter combining with the mixture glass fibers with mixing such that the fibers are evenly dispersed throughout the mixture to form (A)

(c) molding or extruding to form a shaped article which exhibits a coefficient of linear thermal expansion of 4x10^{"5 0}K^"' or less, and (d) joining with a structural article (B) selected from the group consisting of metal sheet, shaped metal article, rigid shaped thermoplastic article, and rigid shaped thermoset article, including combinations.

17. The process of Claim 16 wherein said polyvinyl chloride is a homopolymer of polyvinyl chloride with intrinsic viscosity of from about 0.5 to about 0.7 articles.

18. The process of Claim 16, wherein the amount of plasticizer present is from 40 to 90 weight parts per 100 parts of polyvinyl chloride and said coefficient is reduced to less than 2.0xl0^"5 °K^"'.

19. The process of Claim 16, wherein said plasticizer in (A) is a phthalate ester and said reinforcement material is chopped glass fibers having a diameter of from 8 to 15 μm.

20. The process of Claim 16, wherein said polyvinyl chloride has an intrinsic viscosity of from 0.5 to 0.7 and is present at 100 weight parts, said plasticizer is present at from 20 to 85 weight parts, the reinforcement material is present at from about 5 percent to about 40 percent by weight of the said article, and said coefficient is reduced to less than 1.5xl0^'5 °K^"'.