JPS6315135B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Glass fiber reinforced thermoplastic sheets that can be stamped under heat and pressure into various shapes for automotive applications have been described in the literature. The typical method used to date to make such products is U.S. Patent No.
No. 3664909; No. 3684645; No. 3713962 and No.
This is the method described in No. 3850723. Glass strands used to make manufactured mats are usually treated with a suitable sizing system prior to mat formation. One such system is described in U.S. Patent No.
Described in No. 3849148. The pine used in manufactured thermoplastic sheet products is typically needle processed, as described in U.S. Patent No. 3,883,333.
No. 3664909.

Laminates made by prior art methods and the present invention can be stamped using the methods described in US Pat. Nos. 3,621,092 and 3,626,053.

In the prior art method described above, a sheet product is created by laminating layers of needled pine and thermoplastic resin (typically polypropylene) in a hot platen press. In another method shown in attached Figure 2, the resin and mat are laminated using a continuous laminator.

Although the hot platen press method produces an acceptable product, the manufacturing process itself is poor since the pine and thermoplastic sheets used to make the laminate are hand-laminated and the process is batch-operated in nature. is slow and expensive. In the continuous method shown in Figure 2,
Inadequate control of the pressure applied to the laminate in the cooling section often results in the production of laminates with non-uniform void content.

According to the present invention, a method of continuously making laminated glass fiber reinforced thermoplastics is provided which overcomes many of the drawbacks of the prior art. The method of the present invention passes the glass fiber mat and thermoplastic resin through a lamination zone having two different temperature zones. In the first part of the lamination zone, heat and pressure are applied to the thermoplastic resin and glass mat,
Ensure that the resin remains molten while passing through the zone. The mat and molten resin passing through this zone are given sufficient residence time for the molten resin to flow into the glass mat and sufficiently immerse the mat. The mat and molten resin sheet then enter a cooling zone where it is maintained under pressure to solidify the resin throughout the mat, and at the exit end of the cooling section of the lamination process, a glass fiber reinforced heat with controlled void content is produced. A continuous sheet of plastic resin is provided that can be stamped into a final product using the prior art stamping methods described above.

A variety of thermoplastic resins can be used to make the laminates according to the invention; representative resins suitable for this use include, for example, the homopolymers and copolymers described below. (1) A vinyl resin produced by polymerization of vinyl halide or copolymerization of an unsaturated polymerizable compound and vinyl halide, and the vinyl unsaturated polymerizable compounds used in the copolymerization include, for example, vinyl ester, α, β - unsaturated acids, α, β-unsaturated esters, α, β-unsaturated ketones, α, β-unsaturated aldehydes and unsaturated hydrocarbons such as butadiene, styrene; (2) poly-α-olefins, e.g. (3) phenoxy resins; (4) polyamides such as polyhexamethylene adipamide; (5) polysulfones; (6) polycarbonates; (7) ) polyacetal;
(8) polyethylene oxide; (9) polystyrene, including copolymers of styrene and monomer compounds such as acrylonitrile, butadiene; (10) acrylic resins such as methyl acrylate, acrylamide, methylolacrylamide, acrylonitrile polymers and the like and styrene; (11) neoprene; (12) polyphenylene oxide resin; (13) polymers such as polybutylene terephthalate, polyethylene terephthalate; and (14) cellulose ester; nitrate, acetate, propionate, etc. include.
The above table is not meant to be limiting or exhaustive, but merely to illustrate the wide range of polymeric materials that may be used in the present invention.

Fiberglass mats used in the manufacture of laminates are covered by U.S. Pat. No. 3,883,333, assigned to the assignee of this invention.
No. 5,991,900, which is incorporated herein by reference. In the method described in this patent, mats are formed to the desired depth by placing continuous strands on a conveyor surface, typically an interlocking chain. The strand is typically placed on the chain across a stretcher which projects the strand across the surface width and onto the conveyor surface in a direction transverse to the conveyor's travel. The pine formed in this way is then sent to a needle processing machine. A needling machine is a conventional felt weaving machine with a large number of barbed needles that penetrate the pine and intertwine the continuous strands, thereby simultaneously cutting the strands into random lengths. However, it also provides directional stability to the pine. Needling provides a significant amount of short glass fibers in the finished mat by the action of the barbed needle penetrating the mat depth and cutting a significant number of continuous strands into short staple fibers while penetrating.

As used herein, “short fiber” refers to 25.4 mm (1
(inches) or shorter lengths. The amount of short fiber produced by needle operation varies depending on the speed of needling, the number and type of needles used. Generally, the short fibers present in matt account for 10 to 25% of the matt weight.
Preferably it is 15 to 20 percent. The remaining mats are 25.4 mm (1 inch) or larger, generally from 38.1
Consisting of strands and fibers 11/2 to 5 inches (127 mm) or longer in length. As evident in the above-mentioned US patent, the speed of the needle machine and the mat forming surface are matched to provide a uniform mat density exiting the exit of the needle machine. The needles used have jaws in either the lower or upper position, which, as they pass through the upper surface of the mat, push the fibers from the surface into the interior of the mat, or pull the fibers into the interior from the lower surface of the mat, respectively. In some cases, upwardly and downwardly barbed needles are used to penetrate the strand from both the upper and lower surfaces in one vertical stroke of the needle carrying body. Optionally, the process of the invention can be carried out using chopped strand mats used as the glass source. A representative pine of this type is described in US Pat. No. 2,790,741.

In the practice of this invention, the thermoplastic resin can be supplied to the lamination process in any of a variety of forms.

In some cases, the resin is supplied to the lamination zone in preformed sheets of the desired thickness, the number of sheets depending on the desired thickness of the final product and the mat used. It is within the scope of this invention to supply the thermoplastic resin to the lamination process as a pre-melted extrudate from a high temperature, high pressure extrusion line. In this type of system, the extrudate is typically passed between the lamination surfaces in sheet form from an extrusion die that is maintained at a temperature and pressure sufficient to maintain the resin in a fluid state as it is fed to the lamination zone. Supplied. In typical operations, melt extrudates are fed to the lamination zone as well as sheet thermoplastics, as described in more detail below.

It is also within the scope of the invention to add compatible materials to the laminates made according to the invention that do not affect the basic novel properties of the product.

Such materials include colorants, including dyes and pigments, fillers and similar additives. Antioxidants, bactericidal agents, antistatic agents, stabilizers, and antifouling agents can also be added. As commonly used, the amount of additive is less than 30 percent of the weight of the product, typically 10 to 20 percent.

In practicing the present invention, the lamination process is performed under various pressure and temperature conditions. Accordingly, an initial step in the operation involves contacting the reinforced glass fiber mat with the molten resin, suitably impregnating the mat structure with the resin system used to form the final sheet product. Pressure is applied in the high temperature process section of the laminated system, from 0.3515
8.436Kg/cm ² (5 to 120 pounds per square inch),
Preferably, it can vary from 1.406 to 4.218 Kg/cm ² (20 to 60 pounds per square inch). The high temperature process of lamination typically ranges from 117°C to 288°C.
Controlled within a temperature range of 350°C (350° to 550°C).
This temperature depends somewhat on the melting temperature of the resin used. For example, for polypropylene resin systems, the temperature during the high temperature process of lamination is typically between 204°C and 232°C.
(400〓 to 450〓). The pressures used in the low temperature step of the process are the same or higher than those used in the high temperature step, and are generally within the ranges described above for the high temperature step.

The invention and its advantages over the prior art will be further explained with reference to the accompanying drawings.

As shown in FIG. 2, a double belt laminating machine is used to produce a continuous sheet 2 of resin and glass fiber mat. In the method shown, glass fiber mats 1 and 1' are fed between laminated belts 3 and 4. Molten resin 5 is fed between mats 1 and 1' from an adjustable slot 6 located along the length of extrusion die 7. Two resin sheets 8 and 9 are fed to the laminated belts 3 and 4 above and below the mats 1' and 1, respectively.

The belt 4 passes around rollers 11 and is preheated by a heater 13 before being heated and engaged with a press roll 15. Similarly, belt 3 is press roll 1
5 is preheated by a heater 16. A heater 18 is provided on the heated press roll. Pressure is applied to the laminate 2 by applying tension to the belts 3 and 4. Belts 3 and 4
The tension applied to will create a radial force on the resin mat composite. The radial force and pressure generated serve to saturate mats 1 and 1' with resin;
While applying tension, the heat applied to the sheet 8
and 9 are melted. Roll 24 applies tension to belt 3 and roll 25 applies tension to belt 4.
The material assembled into a resin sheet with glass fibers produced by passing the material through the press roll 15 then passes through the cooling roll 20 between the belts 3 and 4, and is partially cooled while passing through this roll, but is not completely cooled. It does not solidify. A cooler 21 is provided on the roll 20 to lower the temperature of the belt and resin. After the sheet leaves the roll 20 between the belts 3 and 4,
It is sent to another horizontally long cooling zone 22, where the temperature of the belts 3 and 4 is further lowered to further cool and solidify the mat and resin in the sheet 2. Belt 3 is then reversed at roll 23 to pass over tension roll 24, belt 4 passes through roll 25 back to roll 11, and product 2 is removed at the point where belts 3 and 4 separate.

Although the illustrated lamination process has been used to make useful commercial products, it has certain drawbacks that the present invention overcomes. Immersion pressure is applied to the mat and resin by tension applied to belts 3 and 4 by tension rolls 24 and 25, respectively. Experience has shown that when a pressure of, for example, 2.109 Kg/cm ² (30 pounds per square inch) is applied to the heated press roll 15, only 0.0352 to 0.0703 Kg/cm ² (1/2 to 1/2 1 lb) can be maintained in the cooling zone of zone 22.

This often results in a large amount being deposited in the product due to the tendency of the trapped gases to expand and cause the glass mat to expand while the resin is not fully solidified, thus relieving the pressure on the glass mat. Create a void. The rolls used and the belt curvature required in this device, for example belt 4 being on the outside in the press roll 15 and on the inside in the cooling zone, result in non-uniform belt speeds. Therefore, belts 3 and 4 traveling at the same linear velocity are
Since they pass through the rolls with different radii, they move relative to each other on the rolls.

In the method schematically illustrated in FIG. 1, resin sheets 100 and 101, glass fiber mats 102 and 103, and molten resin 104 are fed between belts 105 and 106 of a continuous laminator. belt 105
and 106 are continuous belts, each having rolls 10
7 and 108 and around rolls 109 and 110.

The laminating machine is 2 designated by 120 and 130 as shown in the figure.
divided into two parts. Only two parts are shown for convenience, as each part can be one or more devices, as will be obvious to those skilled in the art. As shown in the illustrative figures, section 120 is the hot lamination zone of the method and includes an upper hot platen 121 and a lower hot platen 122, which move in a direction perpendicular to the direction of travel of belts 105 and 106. These hot platens 121 and 122 are hydraulically operated and can exert a force of 0 to ³⁰ psig between belts 105 and 106 on the material passing through this lamination zone. . If you change it to a hot plate, you can operate it even at high pressure.
Movement of the material to be laminated in this zone is maintained by a number of rollers 123 and 124 located at the top and bottom of the lamination zone 120, respectively. Rollers 123 and 124 are rods that extend across the width of belts 105 and 106. These rods are sprocket 125 for rod 123 and rod 124.
Its end is connected to a link chain which in turn rides on a sprocket 126 for the engine. Sprockets 125 and 126 are driven by suitable motors, not shown. As can be seen from the drawings, the lamination pressure applied to belts 105 and 106 is transmitted to the belts by rollers 123 and 124 when hot platens 121 and 122 contact the rollers. Rollers 123 and 124 transfer the pressure from medium heat plates 121 and 122 through this zone of the belt to belt 1.
In addition to 05 and 106, belts 105 and 106
is passed through this band 120.

Zone 120 also provides heat that is transferred to the sheet material as it passes through zone 120 to maintain the sheet material in a molten state and thereby infiltrate the resin into the glass matrix of the laminate being formed. let

The laminate is sent from zone 120 to zone 130;
The zone 130 has heating plates 131 and 1 at the top and bottom, respectively.
32 and rollers 133 and 134 are provided. As with zone 120, rollers 133 and 13
4 is moved by sprockets 135 and 136 which feed a chain 137 attached to rollers 133 and 134, the sprockets 135 and 136 being driven by a suitable motor combination, not shown. The heating plates 132 and 131 have laminates in zone 13.
Pressure is applied to the laminate as it passes through the laminate, and a heat transfer fluid is supplied in zone 130 in an indirect heat exchange supply system (not shown) to remove heat from the laminate as it passes through rolls 133 and 134. Cool to solidify all the resin. The solidified finished product 140 is in zone 13
0 and then subjected to slitting, cutting and packaging steps, which steps do not form part of this invention.

As will be apparent to those skilled in the art, the method of the present invention provides significant flexibility in the physical structure of glass fiber reinforced thermoplastic laminates. Therefore, pressure can be applied in hot zone 120 using hot platens 121 and 122 to any desired pressure within the limits of the machine. Generally, the pressure ranges from 0 to 2.109 Kg/cm ² gauge pressure (1/2 to 1 pound per square inch), typically 1.406 to 2.109 Kg/cm ² gauge pressure (20 to 30 psig)
It can be changed up to. Similarly, in hot zone 120, heat can be applied at a temperature range that ensures adequate resin flow throughout the glass fibers while applying pressure for a given linear velocity of conveyors or belts 105 and 106.

Therefore, a temperature of 149°C to 316°C (300〓 to 600〓) is used in zone 120, and a temperature of 121°C to 288°C is used in zone 120.
It is typical to maintain a resin temperature in the range of (250〓 to 550〓). It has been found that a resin temperature range of 204°C to 232°C (400° to 450°C) is preferable for polyolefins.

Operation of zone 130 applies pressure through hot platens 131 and 132 as the laminate from zone 120 enters zone 130 to precisely control the void volume of finished laminate 140, as shown in FIG. This is a condition that has not been possible until now with various continuous lamination methods.

Therefore, if the pressure in zone 130 is kept higher than the pressure in zone 120, a low or nearly voided product will be obtained. For example, in a typical operation of the system shown in Figure 2, 2.109
In the case of polypropylene lamination with glass fibers at Kg/ ^cm2 gauge pressure (30 psig), a pressure lower than 0.0703 Kg/ ^cm2 gauge pressure (1 psig) is achieved in the cooling zone 22, producing a product of 8 to 10 volumes. % void content. 2.109 in both the hot zone 120 and the cooling zone using the method shown in Figure 1.
Kg/cm ² Gauge pressure (30 psig) is added, 3 to 4
Products with volume percent voids are typical. Lower void volume contents can easily be obtained by using higher pressures in the cooling zone 130 than in the heating zone.

Void content can be controlled to a certain extent using only molten resin without resorting to laminated systems using sheet products.

Therefore, using molten resin 104 together with mats 102 and 103, overlay sheets 100 and 1
By eliminating 01, the resulting laminate has significantly lower void volume than the product obtained using the overlay resin sheet. If surface appearance is not of paramount importance, this provides a useful continuous production system for low void volume laminates. This, combined with careful control of the pressure in the cooling zone of the lamination process to maintain it equal to or greater than the pressure in the heating zone of the process, results in a product with consistently low void volume throughout.

Generally, the glass fiber mats used in the production of laminates according to the present invention are needled into complete mats and cut filaments and strands are fed into the mats, so that after needling the mats have an inherent to 25 weight percent staple fibers (i.e., fibers 25.4 mm (1 inch) or less in length), with the remainder of the mat consisting of long strands. Continuous strand mats can be formed from fibers ranging in diameter from "T" to "G" or smaller diameters by the method of U.S. Pat. No. 3,883,333. The fiber strands used to make mats are typically bundles of 50 fibers or less, although bundles of fibers having 100 or more filaments can be used.

Continuous strand mats can be made directly from bushings as described in U.S. Pat.
It can be made by placing the strands on a conveyor in a manner similar to that described in No. 3,883,333.

In FIG.
and 103 with a melt extrudate 104 placed between. Although this method represents the preferred method of operation, the method need not be performed in this manner. It is contemplated that the process of the present invention can be carried out using multiple extrudates from individual extruders or from a single multi-head extruder. In the latter case, the mat is fed in such a way that the extrudate is fed inside and outside the glass mat. The advantage of using extrudates in place of film layers 100 and 101 is that the extrudate heat of the molten thermoplastic does not require the heat load in hot zone 102 required to melt the films 100 and 101, and therefore the machine This means that there is no need to apply the heat load that would be applied when using a film. or,
It is also contemplated that a single mat may be used in combination with preformed thermoplastic films or extrudates alone. In the case of a single mat construction, it is preferred to use an extrudate rather than a film as the thermoplastic source. As mentioned above, if possible, heat is applied primarily to the resin used by the extruder;
It is desirable to use extrudates because the total energy input to the system can be further reduced through the indirect heat exchange system in the hot zone of the laminator.

Although the invention has been described with respect to particular embodiments, it is not intended to be limited thereby other than as described in the claims below.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a laminating machine suitable for making glass fiber reinforced thermoplastic sheets according to the present invention. FIG. 2 is a schematic diagram of a continuous lamination process currently used to produce glass fiber reinforced thermoplastic sheets suitable for stamping.

Claims (1)

[Scope of Claims] 1. A method for producing a glass fiber reinforced thermoplastic resin sheet having a low void content, comprising: (a) straightening two needle-processed nonwoven glass fiber mats between two belts; (b) introducing molten thermoplastic resin between said mats into said heated lamination zone; and (c) continuously passing said belt through said mats and said molten thermoplastic resin. The mat and the molten thermoplastic are heated by applying pressure and providing sufficient heat to the zone to maintain the molten thermoplastic in a molten state and provide a temperature sufficient to sufficiently wet the mat with the thermoplastic. (d) removing heat from the mat and molten thermoplastic resin in the cooling zone to solidify the molten thermoplastic resin into a solid thermoplastic resin-mat sheet; The thermoplastic resin is cooled during a straight pass through said cooling zone in order to cool the mat and molten thermoplastic resin for a sufficient period of time and at the same time keep the level of voids in the cooling zone as low as the level in the heated lamination zone. maintaining the pressure on the resin and the mat at least equal to the pressure applied to the molten thermoplastic and the mat in the heated lamination zone; A manufacturing method characterized in that a solid sheet is removed in a straight path. 2 The pressure in the heating lamination zone is 1.406 to 2.109Kg/cm ²
(20-30psi) and the pressure in the cooling zone is 1.406
2. The method of claim ¹ , wherein the pressure is at least as high as the pressure in the heated lamination zone at 20-30 psi. 3. A method for producing a glass fiber reinforced thermoplastic resin sheet having a low void content, comprising: (a) two needle-processed nonwoven glass mats, a molten thermoplastic resin and two thermoplastic film sheets; (b) the belt is fed in a straight path between the laminated belts to a heated lamination zone; (c) the molten thermoplastic resin is fed between the needled nonwoven glass mats to form a thermoplastic film; (d) sheets are provided on the outside of each of said needled nonwoven glass mats, each laminated belt is placed on top of each of said thermoplastic films, and (d) the mat and said molten thermoplastic resin and thermoplastic film are As it passes through the heated lamination zone, it applies pressure through the belt and (e) an amount of heat sufficient to maintain the temperature in the heated lamination zone high enough to cause the film to become molten. Introducing (f)
laminating the resulting molten thermoplastic resin and the needled nonwoven glass mat between the belts for a time sufficient to sufficiently impregnate the needled nonwoven glass mat during passage through the heated lamination zone; g) the resulting needle-processed nonwoven glass mat impregnated with molten thermoplastic resin is continuously conveyed in a straight path from the heated lamination zone together with the lamination belt into a cooling zone; The pressure in the cooling zone is maintained at least equal to the pressure used in the heated lamination zone through the belt over a needled non-woven glass mat impregnated with molten thermoplastic resin to keep it as low as in the heating lamination zone; (i) an amount of heat sufficient to provide a temperature low enough to solidify the molten thermoplastic in the cooling zone while the sheet is under pressure;
The molten thermoplastic resin is removed from the impregnated needled nonwoven glass mat, thereby forming a solid sheet of glass fiber reinforced thermoplastic resin, and (n) glass fibers having a low void content are continuously removed from the cooling zone. A manufacturing method characterized in that a solid sheet of reinforced thermoplastic resin is removed in a straight path. 4 The pressure in the heating lamination zone is 1.406 to 2.109 Kg/cm ²
(20-30psi) and the pressure in the cooling zone is 1.406
4. The method of claim ³ , wherein the pressure is at least as high as the pressure in the heated lamination zone at 20-30 psi.