JP3467745B2 - Film produced by bubble formation of a composition comprising polyamide and functionalized polyolefin - Google Patents

Description

Description: BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to polyamide-containing films produced by bubble molding of compositions, which are useful, for example, as support webs during the production of composites.

Description of the Prior Art Significant technological progress has been made in the field of reinforced plastics. The need for lighter, more energy-efficient cars has spurred the need for research activities in the field to develop plastics with sufficient strength and durability to replace the metal structural support components of the car body. Is spent on manufacturing. Reinforced plastic parts must not only have the same structural strength and integrity as such metal parts, but at the same time be lightweight and at the same or preferably cheaper cost. As a result, a great deal of effort has been put into developing high-strength structural materials.
By making the most of materials and similar materials, relatively fast matched die forming method became possible.

The SMC contains, among other things, unsaturated polyesters, crosslinkable polymeric resins including styrene monomers (crosslinking agents), particulate fillers, chopped fiber reinforcement and various other minor additives. This composite material is applied on a liquid resin layer supporting chopped fibers on a moving polyamide film, and another polyamide film layer (which may be further coated with another liquid resin layer) is placed thereon. It is common practice to prepare a sandwich composite by passing it through a series of kneading and compression rolls and winding it into large rolls or loops for storage. After aging for about 2-5 hours to increase the viscosity of the material to a consistency that allows molding, SMC is used to manufacture molded parts such as automobiles and boats. The production is carried out by cutting an appropriate size from a roll or the like, peeling off the polyamide carrier film, and putting the SMC in a heating mold to completely cure it while molding. Thus, SMC sandwich composites are used in compression molding processes, especially matched die molding processes. A similar material, Thick Molding Material (TMC), is also manufactured in a similar process. TMC is most often used in injection molding.

Polyamide-containing films are useful in the production of SMC and TMC. This is because polyamide is relatively impermeable to styrene monomers and has good strength. Co-owned U.S. Pat. No. 4,444,829 suggests that films formed from blends of polyamide and various polyolefins are excellent carrier films for making sandwich composites of this type. This patent specification describes the production of this film by an injection molding process. Also, in this patent specification, a copolymer of nylon 6 and ethylene vinyl acetate is described as a preferred product. This product has been used as a useful product in the industrial world, and it has excellent strength and SM.
It is impermeable to the styrene component of C and has excellent releasability from SMC. Additionally, cast films prepared from blends of nylon 6,6 and modified polypropylene have been utilized.

It has been desired to produce a film that is easy to fit on a roll by the blown film preparation method. However, a problem faced by the film manufacturing industry is that the molecular weight of polyamides is relatively low (eg, less than about 120 for nylon 6 as measured by formic acid viscosity), making it impossible to blow out films. . As is known to those skilled in the art, blown film extrusion involves passing a plasticized film composition through an annular die head to form film bubbles. The bubbles eventually collapse and form within the film. For example, Modern Plastics Encyclopedia 1992 24
See pages 5-248. Ethylene with a formic acid viscosity of less than about 120
Vinyl acetate copolymer and polyamide 6 do not form stable bubbles in the film by the blown extrusion method.

Using a low molecular weight polyamide, it is possible to manufacture a film that maintains excellent strength and styrene impermeability and is easily peeled from the composite components of the film by, for example, the blown film manufacturing method for manufacturing a composite material such as SMC. desirable.

SUMMARY OF THE INVENTION The present invention addresses the above-mentioned problems faced by the film manufacturing industry, which cannot be produced by inflation, and provides a composition that maintains bubble strength during inflation. This composition contains a relatively low molecular weight polyamide (nylon 6, formic acid viscosity less than about 120).
And a minimum amount of polyolefin having a reactive group.

Thus, the present invention provides (a) a polyamide having a formic acid viscosity of about 20 to about 120, measured by ASTM D-789, of from 50% to 99.9% by weight of the total composition, and (b) the composition. By bubble forming from a composition comprising a polyolefin containing from about 0.1% to less than 1% by weight of the total weight of functional groups reactive with the functional groups of said polyamide in an amount sufficient to maintain bubble foam strength. Provide the manufactured film.

The present invention comprises (a) from about 50% to about 9% by weight of the total composition.
About 9.9% by weight of formic acid viscosity measured by ASTM D-789 is about
20 to about 120 polyamides, and (b) about 0.1% to less than about 1% by weight of the total weight of the composition of functional groups reactive with the functional groups of the polyamide, about 0.01% by weight of the total polyolefin. A film made by bubble molding from a composition, preferably from about 0.01 to about 10% by weight of the polyolefin, and (c) from about 5% to about 50% by weight of the total composition of the non-functionalized polyolefin. provide.

The present invention also provides a method of forming a polyamide-containing film from bubbles. The improvement of this method is that (a) from about 50% to about 99.9% by weight of the total composition of ASTM D-
Polyamide having a formic acid viscosity of about 20 to about 120, as measured by 789, and (b) about 0.1% to less than about 1% by weight of the total weight of the composition of a functional group that reacts with the functional groups of the polyamide. Bubble molding from a composition containing a polyolefin contained in an amount sufficient to maintain strength.

Detailed Description of the Preferred Embodiments As mentioned above, the film of the present invention comprises a polyamide and a functionalized olefin, and preferably also a non-functionalized polyolefin. The polyamides used in the present invention are characterized by the repeated presence of carboxamides as an integral part of the polymer chain separated from each other by at least two carbon atoms. These polyamides have the following general formula: —NHC (O) RC (O) NHR ¹ — or —NH—R—C.
Examples thereof include a monomer repeating unit represented by (O)-or those having a combination thereof. In the above formula,
R and R ^{1, which} may be the same or different, are alkylene having 2 or more carbon atoms, preferably 2 to 12 carbon atoms. The polyamides of the present invention have a relatively low molecular weight and a formic acid viscosity (FAV) of about 50 to about 120 (measured by ASTM D-789).
Is preferred. In this method, 100m of 90% formic acid at 25 ℃
A solution prepared by dissolving 11 g of polyamide in 1 is used.

Specific examples of useful polyamides include polyamides obtained by the reaction of diamine and diacid. For example, poly (tetramethylene adipamide)
(Nylon 4,6); Poly (hexamethylene adipamide) (Nylon 6,6); Polyhexamethylene azelainamide (Nylon 6,9); Poly (hexamethylene sebacinamide) (Nylon 6,10); Polyhexa Methylene isophthalimide (nylon 6, I); polyhexamethylene terephthalimide (nylon 6, T); poly (heptamethylene pyramide) (nylon 7,7); poly (octamethylene suberamide) (nylon 8.8); poly ( Nonamethylene azelamide) (nylon 9,9); poly (decamethylene azelamide) (nylon 10,9); and the like. Moreover, as a useful polyamide, a polyamide produced by polymerizing an amino acid or a derivative thereof (for example, lactam) can be exemplified. Examples of these useful polyamides are poly (4-aminobutyric acid) (nylon 4); poly (6-aminohexanoic acid).
[Poly (also known as caprolactam)] (nylon 6); poly (7-aminoheptanoic acid) (nylon 7); poly (8-aminooctanoic acid) (nylon 8);
Poly (9-aminononanoic acid) (nylon 9); Poly (10
-Aminodecanoic acid) (nylon 10); poly (11-aminoundecanoic acid) (nylon 11); poly (12-aminododecanoic acid) (nylon 12) and the like.
Blends of two or more polyamides may be used.

Other polyamides that can be used are adipic acid and metaxylenediamine (nylon MXDA); adipic acid, azelaic acid and 2,2-bis- (p-aminocyclohexyl) propane; terephthalic acid and 4,4'-diamino. Examples thereof include those obtained from dicyclohexylmethane and the like.

Copolymers obtained from repeating units of the above polyamides can also be used. Such polyamides include carboractam / hexamethylene adipamide copolymer (nylon 6 / 6,6); hexane methylene adipamide /
Caprolactam copolymer (nylon 6,6 / 6); trimethylene adipamide / hexamethylene azelaiamide copolymer (nylon trimethyl 6,6 / 2,2); hexamethylenadipoamide / hexamethylene-azelaiamide / caprolactam copolymer Examples thereof include (nylon 6,6 / 6,9 / 6), but are not limited thereto.

Preferred polyamides for use in the present invention are poly (caprolactam) (nylon 6); poly (hexamethylene adipamide) (nylon 6,6) and blends and copolymers thereof. The most preferred polyamide is poly (caprolactam).

Polyamides useful in the present invention may be procured from commercial sources or may be manufactured by known manufacturing methods.

As mentioned above, the polyamides of the present invention have a relatively low molecular weight. The FAV of polyamides is about 20 to about 120, preferably about 50 to about 120. It has a molecular weight of about 10,000 to about 3
Equivalent to 5,000. The molecular weight is preferably from about 20,000 to about 30,000.

The polyamide is included in up to about 99.9% by weight of the total composition, more preferably about 50 to about 99.9% by weight of the total composition, and most preferably about 75 to about 99.9% by weight of the total composition.

The polyolefin used in the present invention has about 2 to 2 carbon atoms.
Polymers of about 6 alpha olefin monomers, homopolymers, copolymers (including graft copolymers) and terpolymers of alpha olefins can be exemplified. Examples of homopolymers include low density, linear low density,
Medium density, high density polyethylene; polypropylene; polybutylene; polybutene-1; poly-3-methylbutene-1;
Examples are polypen-1; poly-4-methylpentene-1; polyisobutylene and polyhexene. Examples of copolymers and terpolymers include copolymers and terpolymers of alpha olefins with other olefins. Such other olefins include ethylene-propylene-copolymers; ethylene-butene-copolymers; ethylene-pentene-copolymers; ethylene-
Hexene-copolymers and ethylene-propylene-diene-copolymers (EPDM) may be mentioned. The term polyolefin as used herein also includes acrylonitrile-butadiene-styrene (ABS) polymers. Preferred polymers are those prepared from alpha olefins, most preferred are those prepared from ethylene polymers, copolymers and terpolymers. The above-mentioned polyolefin can be prepared by any known method. The molecular weight of polyolefin is
About 1,000 to about 1,000,000, preferably about 10,000 to about 50
It is 0,000. Preferred polyolefins are polyethylene, polypropylene, polybutylene and their copolymers and blends.

Polyolefins having functional groups useful in the present invention are functional groups of polyamides (amines and / or carboxylic acids).
It is a polyolefin having a functional group that reacts with. Any functional group that reacts with polyamide can be used in the present invention. Preferred functional groups are selected from the group consisting of unsaturated polycarboxylic acids and their acid anhydrides. Among unsaturated polycarboxylic acids and anhydrides, maleic acid, maleic anhydride, fumaric acid, fumaric anhydride, itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride and mixtures thereof are included. Be done. The more preferred functional group is anhydride and the most preferred functional group is maleic anhydride.

The functional group may be introduced by reacting the functional group with a polyolefin. The functional groups can be grafted onto the polyolefin according to known grafting methods. Alternatively, the reactive groups may be copolymerized with the polyolefin backbone. The polyolefin may have one or more functional groups.

Commercially available polyolefins having functional groups that react with polyamides can be preferably used in the compositions of the present invention. Polyolefin having a functional group suitable for the present invention,
It may be prepared according to known methods. Examples of the method include, but are not limited to, the methods described in U.S. Pat.Nos. 3,481,910, 3,480,580, 4,612,155 and 4,751,270. There is no such thing. When graft polymerizing unsaturated carboxylic acids and anhydrides into polyolefins, various methods can be used to initiate the graft polymerization. For example, γ-ray, X-ray, high-speed cathode ray irradiation method or free radical initiation method can be used. Reacting a polyolefin with an unsaturated polycarboxylic acid or anhydride in the presence of free radicals (eg peroxides)
This is the most widely used grafting method. The method using a peroxide is advantageous because no special device or equipment is required for initiating the graft polymerization. Examples of peroxides that can be used include benzoyl peroxide, t-butyl peroxybenzoate, cumene hydroperoxide, and azo compounds such as azo-bis (isobutyronitrile). U.S. Pat. No. 4,612,155 discloses a grafting method using such a radical initiator. Graft yield is 50-
90%. More suitable radical initiators have been initiated in US Pat. No. 4,751,270. Using this radical initiator, a grafting efficiency of up to 100% can be achieved and the grafting specificity for introducing functional groups into the polyolefin can be increased.

The graft polymerization reaction is generally carried out by standard graft polymerization techniques known in the art. For example, it is carried out by heating to a temperature at which the polyolefin melts while kneading the mixture during or after the mixture of the polyolefin, the functional group monomer and the radical initiator. Alternatively, these components may be dissolved or suspended in a suitable solvent to carry out the graft polymerization reaction.

The functionalized polyolefin is greater than or equal to about 0.1 of the total weight of the composition, more preferably about 0.1 to about 10% by weight of the total weight of the composition, and most preferably about 0.
Included from 1 to about 1% by weight.

It has been surprisingly found that the content, based on total weight, of the composition required to maintain the strength of the bubbles formed during blown film production is surprisingly low compared to prior art products. In this regard, U.S. Pat.No. 5,010,136, No. 5,047,479, No. 5,064,700,
See U.S. Pat. Nos. 5,122,570 and 5,126,407. The functional groups of the polyolefin are included in an amount sufficient to maintain the strength of the bubbles formed during film production. The functional groups of the polyolefin are about 0.01 to about 10% by weight of the total weight of the polyolefin, more preferably about 0.1 to about 5% by weight of the total weight of the polyolefin, most preferably about 0.2 to about 1% by weight of the total weight of the polyolefin. Is.

Without intending to be bound by theory, it is believed that the functional groups of the polyolefin react with the functional groups of the polyamide. In other words, the anhydride or acid of the polyolefin is
It is believed to react with amines on the polymer chain ends of polyamides. These reactions cause the polyamide to graft onto the polyolefin. These reactions are believed to increase bubble strength.

Unlike carboxylic acids and anhydrides, the esters of polyolefins do not react with, or only slightly react with, the amines at the ends of the polyamide polymer chains. This is believed to explain why no bubbles are formed when trying to make blown films from a blend of ethylene-vinyl acetate copolymer and polyamide 6. For this reason, blends of polycarbonamide and ethylene-methyl acetate-olimer described in U.S. Pat.No. 3,472,916, and polyamides and ethylene-methyl acrylate-methacrylic acid described in U.S. Pat.No. 4,176,358. Compositions such as blends are also believed to be unable to form bubbles.

The present invention preferably further comprises a non-functionalized polyolefin. This non-functionalized polyolefin includes the above-mentioned polyolefin which does not have the above-mentioned functional group. These include alpha olefin monomers having from about 2 to about 6 carbon atoms, homopolymers, copolymers (including graft copolymers), and terpolymers of alpha olefins. Unlike the above-mentioned polyolefins that have functional groups, non-functionalized polyolefins have no functional groups (ie, are not functionalized). As homopolymers, low density, linear low density, medium density or high density polyethylene; polypropylene; polybutylene; polybutene-1, poly-
Examples thereof include 3-methylbutene-1; polypentene-1; poly-4-methylpentene-1; polyisobutylene and polyhexene. Examples of copolymers and terpolymers include copolymers and terpolymers of alpha olefins with other olefins. Such other olefins include ethylene-propylene-copolymers; ethylene-butene-copolymers; ethylene-pentene-copolymers; ethylene-hexene-copolymers and ethylene-propylene-diene-copolymers (EPDM).
Can be illustrated. The above-mentioned polyolefin can be prepared by any known method. The molecular weight of the polyolefin is from about 1,000 to about 1,000,000, preferably about
10,000 to about 500,000. Preferred polyolefins are polyethylene, polypropylene, polybutylene and their copolymers and blends. Non-functionalized polyhexenes are generally cheaper than other non-functionalized polyhexenes and exhibit good strippability when the films of the invention are used to make SMC, TMC or other composite sandwich composites.

The unfunctionalized polyolefin is preferably about 5 to about 50% by weight of the total composition, more preferably about 5 to about 40% by weight of the total composition, and most preferably about 5 to about 25% of the total composition. It is preferable to include it by weight%.

The film of the present invention contains polyamide, a polyolefin having a functional group, and optionally a non-functionalized polyolefin, and a small amount of various commonly used additives such as a pigment, a heat stabilizer and an antistatic agent. It may be produced by thorough mixing. The pigment is preferably used so that it is easy to see that the release film has been completely removed from the composite. Pigments of this type may be included in any desired amount, such as from about 0.01 to about 2% by weight of the composition, more preferably from about 0.1 to about 1.5%.

As described above, the film of the present invention is manufactured through the bubble forming process. The film manufacturing apparatus used in this process is a blown film (brown fi
lm) device. The manufacturing apparatus has an annular die head for blown film, and the plasticized film composition is supplied through the die head to form bubbles in the film. The bubble eventually breaks and becomes entrapped in the film.

The film of the present invention can be of any desired thickness.
A typical thickness is less than about 16 mils (400 μm) and a preferred thickness is from about 0.2 mils to about 10 mils (about 5 μm to about 250 μm).
m), a more preferred thickness is about 0.4 mils to about 5 mils (about 10 μm to about 130 μm), and a most preferred thickness is about 0.5 mils to about 2 mils (about 12.5 μm to about 50 μm). A thickness of this order results in a fairly flexible film, but thicknesses outside these ranges can be employed to meet specific needs and such cases are also covered by the invention. Should be understood.

The films of the present invention can be stretched or oriented in any direction if desired using methods known in the art. In this stretching operation, the film is moved in the direction of movement of the blown film ("machine direction" in the art).
rection) ") or in a direction perpendicular to the machine direction (" transverse direction "in the art) to form a uniaxially stretched film, or to both directions to form a biaxially stretched film. May be. When it is stretched in both directions, it may be stretched simultaneously or separately.
If the film is stretched after manufacture, it is typically stretched through a series of preheat and heated rolls. The heated film passes through a pair of nip rolls,
The speed after passing through should be faster than the speed before passing. This speed change is compensated by the stretching of the film. Typical methods and range of conditions for preparing uniaxially oriented polyamide films are disclosed, for example, in US Pat. No. 4,362,385.

As explained above using pigments in the composition,
In the production of SMC, TMC and other composites, the film does not stick or barely sticks to the compound, and the release film has sufficient release adhesion or release to allow the film to be easily peeled off from the composite prior to molding. Is important to have.

Typical SMC and TMC compound compositions are known in the art. For example, it is disclosed in the above-referenced co-owned US Pat. No. 4,444,829, which is incorporated herein by reference.

The film of the present invention exhibits release properties suitable for use as various release films. The film of the present invention is
It can be used in particular for the production of prepreg materials, SMC, TMC and bulk molding materials (BMC). The films according to the invention can also be used as support webs, especially for the production of fiber reinforced panels (FRP). In these steps, the support film can be used in the manufacturing process.

The manufacturing process of SMC is such that the thermosetting resin layer is cast in a liquid state on the continuously fed film of the present invention, the reinforcing material is introduced on the fed liquid layer, and the other film layer (thermosetting is applied thereon). A composite resin layer may be laminated) to contact the upper surface of the reinforced liquid layer to form a sandwich composite material, and the resulting sandwich composite material is passed through a series of kneading and compression rolls to age the sandwich composite material. Including the operation of winding or looping.

The TMC manufacturing process involves injecting discontinuous reinforcing fibers (ie chopped fibers of desired length) with a resin paste and applying the infused fiber / resin composite to a moving support release film of the present invention, The composition is applied by sandwiching the composition by applying a second release film of the present invention, and further compressing the composition by passing the sandwich composition through a compression area to form a sheet that is generally thicker than SMC. Includes the step of cutting to a desired length for packing. TMC using release film
The manufacturing process is disclosed, for example, in US Pat. No. 3,932,980.

According to the present invention, a blown film can be provided from a polyamide having a relatively low molecular weight. This film has the desirable physical properties described above,
It is particularly useful as a support web for the production of SMC, TMC and similar composite materials.

The invention will be further described by the following non-limiting examples.

Comparative Example 1 A blend of 90% Nylon 6 (71FAV) and 10% ethylene vinyl acetate copolymer was extruded onto an inflation line using a single screw extruder equipped with a Maddox mixing head screw. Barrel and die temperature is 450-500 ° F (232-260 ° C) and die gap is 0.020-0.040 inches (0.0508-0.1016cm)
I chose Films could not be successfully produced from this blend due to the lack of bubbles.

Further, when a blend of nylon 6 (70 FAV) and 1-20% by weight of unmodified polyolefin (a linear low density copolymer of ethylene and butadiene described below) was used, bubbles were not formed and the film was blown to form a film. It could not be manufactured. In addition, nylon 6
When a blend of (130FAV) and 20% by weight of the above polyolefin was similarly used under the above conditions, bubbles were not formed,
No film could be produced by this method.

Example 1 Nylon 6 (85FAV) 90% by weight of Allied Cynal
And 0.5% by weight of the malonic anhydride-modified polyolefin described below and 9.5% by weight of the unmodified polyolefin described below were extruded under the conditions of Comparative Example 1 above. Film thickness 0.0005-0.00 at expansion ratio 1.6-2.3
Bubbles with excellent stability of 2 inches (0.00127-0.00508 cm) were formed.

Comparative Example 2 and Examples 2 and 3 Comparative Example 2 is a film made by inflation using a blend of 90% by weight Nylon 6 (135FAV) and 10% by weight copolymer of ethylene and vinyl acetate.

In Example 2, 94% by weight of nylon 6 (85FAV) and a linear low density poly (ethylene-modified with maleic anhydride were used.
Butadiene) copolymer (0.3% by weight of maleic anhydride,
A composition comprising a density of 0.904, a melt index of 3.0) 1% by weight, and a linear low density poly (ethylene-butadiene) copolymer (density of 0.900, melt index of 5.0). The film was produced by inflation as above.

In Example 3, 90% by weight of nylon 6 used in Example 2, 1% by weight of the maleic anhydride-modified polyolefin used in Example 2, and 9% by weight of unmodified polyolefin used in Example 2 were used. It is a composition consisting of The film was produced by inflation as above.

Testing of these films revealed the following properties. In the table below, COF represents the coefficient of friction. If two values are shown, the first value is the machine direction value and the second value is the transverse direction value.

The peelability of the film of the present invention was comparable to the film of the comparative example. Further, the styrene impermeability and strength were similar to those of the comparative film.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Altman, Carl Elliot Pennsylvania, USA 17964, Pittman, Earl Dee 1, Bocks 118 Sea (72) Inventor McKee, Joseph Edgar United States New Jersey 07936, East Hanover , Gale Drive 51 (72) Inventor Davis, Henry Irvine Second Avenue 1827 (56), Pottsville, PA 17901, USA United States Pennsylvania 1827 (56) References European Patent Application Publication 519617 (EP, A 1) (58) Int.Cl. ⁷ , DB name) C08L 23/00-23/36 C08L 77/00-77/12 WPI / L (QUESTEL)

Claims (9)

(57) [Claims] 1. A polyamide having a formic acid viscosity of 20 to 120, measured by ASTM D-789, of 50% to 99.9% by weight of the total composition, and (b) an amine or carboxylic acid of said polyamide. A sheet-shaped molding material produced by directly bubble-molding a molten solid composition containing a polyolefin having a reactive functional group of 0.01% by weight or more based on the total weight of the polyolefin, and containing 0.1% to less than 1% by weight of the total composition. Carrier film. 2. A film according to claim 1, which comprises from 5% to 50% by weight of the total weight of the composition of (c) a non-functionalized polyolefin. 3. The thickness of the film is from 5 microns to 400.
The film of claim 1 which is micron. 4. The polyamide is nylon 6 or nylon.
The film of claim 1, selected from the group consisting of 6,6, blends and copolymers thereof. 5. The film of claim 1, wherein the polyamide is nylon 6. 6. The film of claim 1, wherein the polyamide is nylon 6,6. 7. The film of claim 1, wherein the polyamide has a formic acid viscosity of 50 to 120. 8. The film of claim 1 wherein said polyolefin functional groups comprise from 0.01% to 10% by weight of the total polyolefin. 9. The polyolefin is low density polyethylene, linear low density polyethylene, medium density polyethylene, high density polyethylene, polypropylene, polybutylene, polybutene-1, poly-3-methylbutene-1, polypentene-1, poly-4. Selected from the group consisting of methylpentene-1, polyisobutylene, polyhexene, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-pentene copolymer, ethylene-hexene copolymer, ethylene-propylene-diene copolymer and acrylonitrile-ptadiene-styrene copolymer. The film of claim 1, wherein