U.S. patent application number 09/738620 was filed with the patent office on 2002-08-15 for flame retardant polyester compositions.
Invention is credited to Aouraghe, Tieb, Gosens, Johannes Cornelis, Wit, Gerrit de.
Application Number | 20020111403 09/738620 |
Document ID | / |
Family ID | 24968766 |
Filed Date | 2002-08-15 |
United States Patent
Application |
20020111403 |
Kind Code |
A1 |
Gosens, Johannes Cornelis ;
et al. |
August 15, 2002 |
Flame retardant polyester compositions
Abstract
A halogen-free, flame retardant polyester composition comprises,
based on the total composition, (a) A poly(ethylene terephthalate)
with a molecular weight of at least 50,000 or a blend of
poly(ethylene terephthalate) with another polyester, taking into
account that the ratio poly(ethylene terephthalate)/other polyester
should be at least 55/45. (b) A combination of at least one
N-containing compound, selected from the group of triazine,
guanidine, or (iso)cyanurate compounds, and at least one
P-containing compound, selected from the group of BPA-diphosphates
or phosphoramides with the proviso that the ratio of the total
amount of P- and N-containing compounds over the total polyester
amount should be between 0.3 and 0.6 and the ratio of the
P-containing compound over the N-containing compound should be
higher than 0.8. (c) An anti-dripping agent in an amount of 0.01-2
weight percent of the total composition. (d) A reinforcing filler
in an amount of 040 weight percent of the total composition.
Inventors: |
Gosens, Johannes Cornelis;
(Roosendaal, NL) ; Wit, Gerrit de; (Ossendrecht,
NL) ; Aouraghe, Tieb; (Vlissingen, NL) |
Correspondence
Address: |
CANTOR COLBURN, LLP
55 GRIFFIN ROAD SOUTH
BLOOMFIELD
CT
06002
|
Family ID: |
24968766 |
Appl. No.: |
09/738620 |
Filed: |
December 15, 2000 |
Current U.S.
Class: |
524/101 ;
524/127; 524/138; 524/139; 524/148; 524/430; 524/437; 524/445;
524/449; 524/451; 524/492; 524/493; 524/494; 524/497 |
Current CPC
Class: |
C08K 5/5399 20130101;
C08K 5/5399 20130101; C08K 5/3492 20130101; C08K 5/31 20130101;
C08K 5/31 20130101; C08K 5/523 20130101; C08K 5/523 20130101; C08K
5/3492 20130101; C08L 67/02 20130101; C08L 67/02 20130101; C08L
67/02 20130101; C08L 67/02 20130101 |
Class at
Publication: |
524/101 ;
524/127; 524/138; 524/148; 524/139; 524/492; 524/493; 524/494;
524/430; 524/437; 524/449; 524/445; 524/451; 524/497 |
International
Class: |
C08L 001/00 |
Claims
What is claimed is:
1. A halogen-free, flame retardant polyester composition comprises,
based on the total composition, (a) A poly(ethylene terephthalate)
with a molecular weight of at least 50,000 or a blend of
poly(ethylene terephthalate) with another polyester, taking into
account that the ratio poly(ethylene terephthalate)/other polyester
should be at least 55/45, (b) A combination of at least one
N-containing compound, selected from the group of triazine,
guanidine, or (iso)cyanurate compounds, and at least one
P-containing compound, selected from the group of BPA-diphosphates
or phosphoramides with the proviso that the ratio of the total
amount of P- and N-containing compounds over the total polyester
amount should be between 0.3 and 0.6 and the ratio of the
P-containing compound over the N-containing compound should be
higher than 0.8, (c) An anti-dripping agent in an amount of 0.01-2
weight percent of the total composition, (d) A reinforcing filler
in an amount of 0-40 weight percent of the total composition.
2. The composition of claim 1, further comprising up to about 40
weight percent of glass fiber.
3. The composition of claim 1, wherein the other polyester resin is
derived from an aliphatic or cycloaliphatic diol, or mixtures
thereof, containing from 3 to about 10 carbon atoms and at least
one aromatic dicarboxylic acid.
4. The composition of claim 1, wherein the other polyester has
repeating units of the following general formula: 5wherein n is an
integer of from 3 to 6, and R is a C6-C20 aryl radical comprising a
decarboxylated residue derived from an aromatic dicarboxylic
acid.
5. The composition of claim 1, wherein the ratio of the total
amount of P- and N-containing compounds over the polyester is
between 0.35 and 0.58.
6. The composition of claim 1, wherein the ratio of the
P-containing compound over the N-containing compound is between 0.8
and 2.5
7. The composition of claim 1, wherein the ratio of the
P-containing compound over the N-containing compound is higher than
1.0
8. The composition of claim 7, wherein the ratio of the
P-containing compound over the N-containing compound is between 1.0
and 3.0, and preferably between 1.2 and 2.5
9. The composition of claim 1, wherein the N-containing compound is
a melamine derivative as melamine cyanurate, melamine pyrophosphate
or melamine polyphosphate.
10. The composition of claim 1, wherein the phosphorus-based
compound is a bisphenolic diphosphate as bisphenol
A-diphosphate.
11. The composition of claim 1, wherein the phosphorus-based
compound is a phosphoramide compound as tetraxylyl piperazine
diphosphoramide.
12. The composition of claim 1, wherein the anti-dripping agent is
present in an amount of 0.02-2 weight percent of the total
composition, and preferably in an amount between 0.05 and 1 weight
percent.
13. The composition of claim 1, wherein the anti-dripping agent is
poly(tetrafluoroethylene).
14. The composition of claim 1, further comprising up to about 60
weight percent of alumina, amorphous silica, anhydrous aluminum
silicates, mica, feldspar, clays, talc, glass flake, glass fibers,
glass microspheres, wollastonite, metal oxides such as titanium
dioxide, zinc oxide, ground quartz, and mixtures thereof.
Description
FIELD OF THE INVENTION
[0001] This invention relates to thermoplastic polyester
compositions, and in particular to halogen-free, flame retardant
thermoplastic polyester compositions.
BACKGROUND OF THE INVENTION
[0002] Thermoplastic polyester compositions, such as poly(alkylene
terephthalates) have valuable characteristics including strength,
toughness, high gloss and solvent resistance. Polyesters therefore
have utility as materials for a wide range of applications, from
automotive parts to electric and electronic appliances. Because of
their wide use, particularly in electronic applications, it is
desirable to provide flame retardancy to polyesters. One particular
set of conditions commonly accepted and used as a standard for
flame retardancy is that which is set forth in Underwriter's
Laboratories, Inc. Bulletin 94 which proscribes certain conditions
by which material are rated for self-extinguishing characteristics.
Another set of conditions commonly accepted and used (especially in
Europe) as a standard for flame retardancy is the so-called Glow
Wire Test (GWT), the International standard IEC 695-2-1/2.
[0003] Numerous flame retarding agents for polyesters are known,
but many contain halogens, usually bromine. Halogenated flame
retardant agents are however less desirable because of the
increasing demand for ecological friendly ingredients. Alternative
flame retarding agents have therefore been developed, based on for
instance Nitrogen and/or Phosphorus compounds. A general
disadvantage of these flame retardant ingredients in polyesters is
the negative effect on properties as impact and color stability
upon oven aging. Several N-containing compounds, combined with
P-containing compounds have been described as flame retardants for
polyesters. JP 03-281652 to Mitsubishi Petrochemical, for example,
discloses FR polyester compositions comprising 100 parts of a
polyester resin, 30-250 parts of a filler, 5-50 parts of melamine
cyanurate, and 5-50 parts of a P-containing FR compound. JP
06-157880 to Akzo Kashima, Mitsubishi Petrochemical, describes a
polyester (100 parts) with 30-250 pts of a filler, 5-50 parts of
melamine cyanurate and 5-50 parts of an aromatic phosphate.
JP11209587 to Kaneka discloses a polyester composition with a)
20-59% Glass and mineral filler in a ratio of 3/2-1/4, b) melamine
cyanurate and c) 15-32% P-compound with P-compound/Melamine
cyanurate ratio of 1/1-1/3, and d) 0.01-2% Fluoro resin.
[0004] Above mentioned literature/patents are suitable for the
intended flame-retardant properties, but none of them describes
potential limitations of the claimed composition ingredients and
the claimed amounts for practical use. Not only good flame
retardancy is needed but a combination of good flame retardant
properties with good ductility and color stability upon oven aging.
The herewith described invention overcomes the described
deficiencies.
BRIEF SUMMARY OF THE INVENTION
[0005] Non-halogenated flame retardants for polyesters, based on N-
and P-containing compounds, are described in the literature.
Although good FR-properties can be obtained upon high enough
amounts of the FR-ingredients, the materials lack good mechanical
properties as impact and/or have insufficient color stability upon
heat aging. Desirable enhanced properties and deficiencies can be
overcome by the proper choice of the P-compound and the right
amounts of N- and P-compounds in relation which each other and in
relation with the type and amount of the present polyester. Good
balance of ductility, flame retardancy and color stability upon
oven aging can be obtained by a flame retardant polyester
composition comprising, based on the total composition,
[0006] (a) A poly(ethylene terephthalate) with a molecular weight
of at least 50,000 or a blend of poly(ethylene terephthalate) with
another polyester, taking into account that the ratio poly(ethylene
terephthalate)/other polyester should be at least 55/45.
[0007] (b) A combination of at least one N-containing compound,
selected from the group of triazine, guanidine, or (iso)cyanurate
compounds, and at least one P-containing compound, selected from
the group of BPA-diphosphates or phosphoramides with the proviso
that the ratio of the total amount of P- and N-containing compounds
over the total polyester amount should be between 0.3 and 0.6 and
the ratio of the P-containing compound over the N-containing
compound should be higher than 0.8.
[0008] (c) An anti-dripping agent in an amount of 0.01-2 weight
percent of the total composition.
[0009] (d) A reinforcing filler in an amount of 040 weight percent
of the total composition.
DETAILED DESCRIPTION OF THE INVENTION
[0010] A halogen-free, flame retardant polyester composition
comprises, based on the total composition,
[0011] (a) A poly(ethylene terephthalate) with a molecular weight
of at least 50,000 or a blend of poly(ethylene terephthalate) with
another polyester, taking into account that the ratio poly(ethylene
terephthalate)/other polyester should be at least 55/45
[0012] (b) A combination of at least one N-containing compound,
selected from the group of triazine, guanidine, or (iso)cyanurate
compounds, and at least one P-containing compound, selected from
the group of BPA-diphosphates or phosphoramides with the proviso
that the ratio of the total amount of P- and N-containing compounds
over the total polyester amount should be between 0.3 and 0.6 and
the ratio of the P-containing compound over the N-containing
compound should be higher than 0.8.
[0013] (c) An anti-dripping agent in an amount of 0.01-2 weight
percent of the total composition.
[0014] (d) A reinforcing filler in an amount of 0-40 weight percent
of the total composition.
[0015] The flame retardant polyester composition includes a flame
retarding quantity of one or a mixture of nitrogen-containing
compounds, selected from the group of triazine, guanidine, or
(iso)cyanurate compounds. Examples of such compounds are the
1,3,5-triazine compounds as for instance
2,4,6-triamine-1,3,5-triazine (melamine), melam, melem, melon,
ammeline, ammelide, 2-ureidomelamine, acetoguanamine,
benzoguanamine, diaminephenyltriazine or mixtures thereof.
Especially salts/adducts of these compounds with (iso)cyanuric acid
(as eg melamine cyanurate), boric acid, and/or phosphoric acid
(including the so called melamine polyphosphate) can be used in the
composition. Preferred compounds include the cyanuric acid
derivatives of 1,3,5-triazine-compounds as melamine cyanurate.
[0016] The nitrogen-containing compounds are used in combination
with one or more phosphorous-containing compounds as described
below, since the combination appears to impart better flame
retardant properties than where either component is used alone.
[0017] A suitable class of phosphorous compounds is the class of
diphosphates of the general structure
(OR1)(OR2)P(.dbd.O)--OXO--P(.dbd.O)- (OR3(OR4) (optionally
including some oligomeric higher phosphates), for instance made out
of POCl3, a diphenol compound HO--X--OH with X is a group with at
least 2 aryl unit (such as bisphenol A), and mono-hydroxy
compound(s) ROH (R1, R2, R3, R4 might be equal or different), such
as phenol. Other suitable phosphorus compounds are phosphoramides
such as tetraxylyl piperazine diphosphoramide.
[0018] The phosphoramides have the following general structure:
1
[0019] wherein R1 is an amine residue, and R2 and R3 are
independently an alkoxy residue, aryloxy residue, aryloxy residue
containing at least one alkyl or one halogen substitution or
mixture thereof, or amine residue. It is preferred that the
phosphoramide have a glass transition point of at least about
0.degree. C., preferably of at least about 10.degree. C., and most
preferably of at least about 20.degree. C.
[0020] Another phosphoramide comprises a phosphoramide having a
glass transition temperature of at least about 0.degree. C.,
preferably of at least about 10.degree. C., and most preferably of
at least about 20.degree. C., of the formula: 2
[0021] wherein each A is independently phenyl, 2,6-dimethylphenyl,
or 2,4,6-trimethylphenyl.
[0022] The composition may further optionally comprise various
fillers and other additives known in the art, particular glass
fibers in an amount of up to about 40 weight percent, and 0.01 to
about 2.0 weight percent of at least one anti-dripping agent which
retards the tendency of the composition to drip when subjected to
burning conditions.
[0023] Suitable polyesters that can be blend with the used
poly(ethylene terephthalate) include those derived from an
aliphatic or cycloaliphatic diol, or mixtures thereof, containing
from 2 to about 10 carbon atoms and at least one aromatic
dicarboxylic acid. Preferred polyesters are derived from an
aliphatic diol and an aromatic dicarboxylic acid having repeating
units of the following general formula: 3
[0024] wherein n is an integer of from 2 to 6, and R is a C6-C20
aryl radical comprising a decarboxylated residue derived from an
aromatic dicarboxylic acid.
[0025] Examples of aromatic dicarboxylic acids represented by the
decarboxylated residue R are isophthalic or terephthalic acid,
1,2-di(p-carboxyphenyl)ethane, 4,4'-dicarboxydiphenyl ether, 4,4'
bisbenzoic acid, and mixtures thereof. All of these acids contain
at least one aromatic nucleus. Acids containing fused rings can
also be present, such as in 1,4-1,5- or 2,6-naphthalene
dicarboxylic acids. The preferred dicarboxylic acids are
terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid
or a mixtures thereof.
[0026] The aliphatic polyols include glycols, such as propylene
glycol, butanediol, hydroquinone, resorcinol, trimethylene glycol,
2-methyl-1,3propane glycol, hexamethylene glycol, decamethylene
glycol, cyclohexane dimethanol, or neopentylene glycol.
[0027] Also contemplated herein are the above polyesters with minor
amounts, e.g., from about 0.5 to about 30 percent by weight, of
units derived from aliphatic acids and/or aliphatic polyols to form
copolyesters. The aliphatic polyols include glycols, such as
poly(ethylene glycol). Such polyesters can be made following the
teachings of, for example, U.S. Pat. Nos. 2,465,319 and
3,047,539.
[0028] The most preferred polyesters are poly(ethylene
terephthalate) ("PET") as main polyester, poly(1,4-butylene
terephthalate), ("PBT"), and poly(propylene terephthalate)
("PPTI"). A preferred PBT resin is one obtained by polymerizing a
glycol component at least 70 mole %, preferably at least 80 mole %,
of which consists of tetramethylene glycol and an acid component at
least 70 mole %, preferably at least 80 mole %, of which consists
of terephthalic acid, and polyester-forming derivatives therefore.
The preferred glycol component can contain not more than 30 mole %,
preferably not more than 20 mole %, of another glycol, such as
ethylene glycol, trimethylene glycol, 2-methyl-1,3-propane glycol,
hexamethylene glycol, decamethylene glycol, cyclohexane dimethanol,
or neopentylene glycol. The preferred acid component can contain
not more than 30 mole %, preferably not more than 20 mole %, of
another acid such as isophthalic acid, 2,6-naphthalene dicarboxylic
acid, 2,7-naphthalene dicarboxylic acid, 1,5-naphthalene
dicarboxylic acid, 4,4'-diphenyl dicarboxylic acid,
4,4'-diphenoxyethane dicarboxylic acid, p-hydroxy benzoic acid,
sebacic acid, adipic acid and polyester-forming derivatives
thereof.
[0029] Block copolyester resin components are also useful, and can
be prepared by the transesterification of (a) straight or branched
chain poly(1,2ethylene terephthalate) and (b) a copolyester of a
linear aliphatic dicarboxylic acid and, optionally, an aromatic
dibasic acid such as terephthalic or isophthalic acid with one or
more straight or branched chain dihydric aliphatic glycols.
Especially useful when high melt strength is important are branched
high melt viscosity resins, which include a small amount of e.g.,
up to 5 mole percent based on the terephthalate units, of a
branching component containing at least three ester forming groups.
The branching component can be one which provides branching in the
acid unit portion of the polyester, or in the glycol unit portion,
or it can be hybrid. Illustrative of such branching components are
tri- or tetracarboxylic acids, such as trimesic acid, pyromellitic
acid, and lower alkyl esters thereof, and the like, or preferably,
polyols, and especially preferably, tetrols, such as
pentaerythritol, triols, such as trimethylolpropane; or dihydroxy
carboxylic acids and hydroxydicarboxylic acids and derivatives,
such as dimethyl hydroxyterephthalate, and the like. The branched
poly(1,4-butylene terephthalate) resins and their preparation are
described in Borman, U.S. Pat. No. 3,953,404, incorporated herein
by reference. In addition to terephthalic acid units, small
amounts, e.g., from 0.5 to 15 percent by weight of other aromatic
dicarboxylic acids, such as isophthalic acid or naphthalene
dicarboxylic acid, or aliphatic dicarboxylic acids, such as adipic
acid, can also be present, as well as a minor amount of diol
component other than that derived from 1,4-butanediol, such as
ethylene glycol or cyclohexylenedimethanol, etc., as well as minor
amounts of trifunctional, or higher, branching components, e.g.,
pentaerythritol, trimethyl trimesate, and the like.
[0030] Fillers and other additives known in the art may be employed
to achieve the desired processing and physical characteristics of
the flame retardant polyester composition. Typically, such
stabilizers are used at a level of about 0.01-10 weight percent and
preferably at a level of about 0.05-2 weight percent. The preferred
stabilizers include an effective amount of an acidic phosphate
salt; an acid, alkyl, aryl or mixed phosphite having at least one
hydrogen or alkyl group; a Group IB or Group IIB metal phosphate
salt; a phosphorous oxo acid, a metal acid pyrophosphate or a
mixture thereof. The acidic phosphate salts include sodium
dihydrogen phosphate, mono zinc phosphate, potassium hydrogen
phosphate, calcium dihydrogen phosphate and the like. The
phosphites may be of the formula: 4
[0031] wherein R1, R2, and R3 are independently selected from the
group consisting of hydrogen, alkyl and aryl with the proviso that
at least one of R1, R2, and R3 is hydrogen or alkyl.
[0032] The phosphate salts of a Group IB or Group IIB metal include
zinc phosphate, copper phosphate and the like. The phosphorous oxo
acids include phosphorous acid, phosphoric acid, polyphosphoric
acid or hypophosphorous acid.
[0033] The polyacid pyrophosphates maybe of the formula:
Mz xHyPnO3n+1
[0034] wherein M is a metal, x is a number ranging from 1 to 12 and
y is a number ranging 1 to 12, n is a number from 2 to 10, z is a
number from 1 to 5 and the sum of (xz)+y is equal to n+2.
[0035] Inorganic fillers can impart additional beneficial
properties such as thermal stability, increased density, stiffness
and texture. Typical inorganic fillers include but are not limited
to alumina, amorphous silica, anhydrous aluminum silicates, mica,
feldspar, clays, talc, glass flake, glass fibers, glass
microspheres, wollastonite, metal oxides such as titanium dioxide,
zinc oxide, ground quartz, and t he like. Preferred inorganic
fillers include zinc oxide, barium sulfate and fiberglass as well
as mixtures of the above. Barium sulfate may be in the form of the
naturally occurring barites or as synthetically derived barium
sulfate. The particle size may vary, and is preferably from about
0.1 to about 50 microns, most preferably from about 1 to about 15
microns.
[0036] Where used, fibrous (filamentous) glass can be untreated,
but preferably, it will be treated with silane or titanate coupling
agents, e.g. Useful filamentous glass is well known to those
skilled in the art and is widely available from a number of
manufacturers. For compositions ultimately employed for electrical
uses, it is preferred to use fibrous glass filaments comprised of
lime-aluminum borosilicate glass that is relatively soda free,
commonly known as "E" glass. However, other glasses are useful
where electrical properties are not so important, e.g., the low
soda glass commonly known as "C" glass. The filaments are made by
standard processes, e.g., by steam or air blowing, flame blowing
and mechanical pulling. The preferred filaments for plastic
reinforcement are made by mechanical pulling. Exemplary filament
diameters are in the range from about 0.00012 to 0.00075 inch. The
glass filaments may be bundled into fibers and the fibers bundled
in turn to yarns, ropes or rovings, or woven into mats, and the
like, as is required by the particular end use of the composition.
In preparing the molding compositions, it is convenient to use the
filamentous glass in the form of chopped strands of from about
one-eighth to about 2 inches long., which usually results in
filament lengths between about 0.0005 to 0.250 inch in the molded
compounds.
[0037] When particulate fillers are present, for example in molding
compositions, the compositions include from 0 to about 60 weight
percent, preferably from about 10 to about 50 weight percent, and
most preferably from about 25 to about 40 weight of the total
composition. Glass fibers are typically used in quantities from
about 0 to about 60 weight percent, preferably from about 10 to
about 40 weight percent.
[0038] The compositions may also contain one or a mixture of
reinforcing filler. Suitable fillers include silica; silicates such
as talc or mica; carbon black; and reinforcing fibers, such as
carbon fiber, aramide fiber or glass fiber. Glass fibers may be
composed of E-glass or alkali metal silicate glass and may comprise
short, chopped glass fibers with a circular cross section ranging
in diameter from about 2.times.10-4 to 8.times.10-4 inch and about
0.2 to 2 cm in length. Such glass fibers are normally supplied by
the manufacturers with a surface treatment compatible with the
polymer component of the composition, such as a siloxane or
polyurethane sizing. When used in the composition, the reinforcing
filler is normally included at a level of from about 1 to 40 parts
by weight, more preferably from about 5 to 35 parts by weight, per
100 parts by weight of the total polymer composition.
[0039] The composition may also include one or more anti-dripping
agents which have the properties of preventing or retarding resin
from dripping while the resin is subjected to burning conditions.
Specific examples of such agents include silicone oils, silica
(which also serves as a reinforcing filler), asbestos and
fibrillating-type of fluorine-containing polymers. Examples of
fluorine-containing polymers include fluorinated polyolefins such
as polytetrafluoroethylene, tetrafluoroethylene/hexafluoropropylene
copolymers, tetrafluoroethylene/ethylene copolymers, polyvinylidene
fluoride and polychlorotrifluoroethylene. Preferred such
fluorine-containing polymers have a melt viscosity at 3500C of
about 1.0.times.104 to 1.0.times.1014 poises.
[0040] When used, the anti-dripping agent is added to the
composition at a level of about 0.05 to 5 parts by weight, more
preferably from about 0.1 to 4 parts by weight, based on the weight
of the total polymer composition.
[0041] The compositions may also contain other conventional
additives used in polyester polymer compositions such as
stabilizers, mold release agents, plasticizers and processing
aids.
[0042] Other ingredients, such as dyes, pigments, anti-oxidants,
and the like can be added for their conventionally employed
purposes.
[0043] The compositions can be prepared by a number of procedures.
In an exemplary process, the polyester composition, optional
amorphous additives, impact modifier and filler and/or reinforcing
glass is put into an extrusion compounder with resinous components
to produce molding pellets. The resins and other ingredients are
dispersed in a matrix of the resin in the process. In another
procedure, the ingredients and any reinforcing glass are mixed with
the resins by dry blending, then either fluxed on a mill and
comminuted, or then are extruded and chopped. The composition and
any optional ingredients can also be mixed and directly molded,
e.g., by injection or transfer molding techniques. Preferably, all
of the ingredients are freed from as much as water as possible. In
addition, compounding should be carried out to ensure that the
residence time in the machine is short; the temperature is
carefully controlled; the friction heat is utilized; and an
intimate blend between the resin composition and any other
ingredients is obtained.
[0044] Preferably, the ingredients are pre-compounded, pelletized
and then molded. Pre-compounding can be carried out in conventional
equipment. For example, after pre-drying the polyester composition
(if necessary) e.g., for four hours at 120.degree. C., a single
screw extruder is fed with a dry blend of the ingredients, the
screw employed having a long transition section to ensure proper
melting. On the other hand, a twin screw extrusion machine, e.g.,
an extruder with i.e. intermeshing co-rotating screws can be fed
with resin and additives at the feed port and reinforcing additives
(and other additives) fed downstream. In either case, a generally
suitable melt temperature will be about 230 to 300.degree. C.
[0045] The pre-compounded composition can be extruded and cut up
into molding compounds such as conventional granules, pellets,
etc., by standard techniques.
[0046] The composition can then be molded in any equipment
conventionally used for thermoplastic compositions, e.g., a Newbury
type injection molding machine with conventional cylinder
temperatures, e.g., 230 to 280.degree. C., and conventional mold
temperatures, e.g. 55 to 95.degree. C.
[0047] The following examples illustrate the invention. They are
set forth as a further description but are not to be construed as
limiting the invention thereto. All amounts are by weight
percent.
EXAMPLES
[0048] All formulations are made by dry-blending of ingredients
with exception of BPA-diphosphate, RDP and glass fiber. The blends
are subsequently compounded on a WP 25 mm co-rotating extruder,
where RDP or BPA-DP and Glass are fed separately down-stream the
extruder. Temperature setting was
50-140-265-260-260-260-260-260-275 C, vacuum 0.2 bar and RPM of
300. Molding is done on a Engel 35 tons with temperature setting of
245-255-265-265 (from throat to nozzle) and a mold temperature of
70 C for the PBT-based formulations and 80 C for the PET-based
formulations (or otherwise stated). Prior to molding the pellets
were pre-dried at 120 C for 4 hrs.
[0049] Materials identified in the tables by abbreviations or trade
names are as follows:
[0050] Poly(butylene terephthalate) with Mw of appr. 80,000 (as
expressed as PS molecular weight)
[0051] (Poly(ethylene terephthalate) with Mw of appr. 60,000 or
45,000 (expressed as PS molecular weight).
[0052] RDP Resorcinol diphosphate
[0053] BPA-DP Bisphenol A-diphosphate
[0054] TSAN PTFE/SAN blend of PTFE/SAN=50/50
[0055] X4PIP Tetraxylyl piperazine diphosphoramide
[0056] The flammability of test specimens is evaluated according to
the standard Glow Wire Test (GWT) protocol as described in the
International standard IEC 695-2-1/2. Ratings of 960 GWT indicate
test samples with the best resistance to burning, whereas 850 GWT
rating is a lower degree of resistance to burning if it failed at
960 degrees C.
[0057] The flammability of test specimen is also evaluated
according to the standard UL-94 protocol, vertical burning. Ratings
of V0 indicate test samples with the best resistance to burning,
whereas V1 and V2 ratings in that order indicate a lessening degree
of resistance to burning (V2 with drippings).
[0058] Test specimen are evaluated for Izod Impact in accordance
with ISO 180. The color of test specimen after oven aging during
500 hours at 150 degrees C. were visually inspected.
[0059] Formulations and test results are shown in the table.
Amounts are part by weight. It has been surprisingly found that the
right balance of properties can be obtained. The following are
observations relating to the results. Formulations based on BPA-DP
or X4PIP do not show dark brown discoloration upon oven aging (500
hrs at 150 C), in contrast to RDP-containing formulations
(Reference samples #1, #3 and #4). Samples with a PET/PBT
ratio<55/45 (Reference samples #1, #2, and #3) do not have a V0
rating, even not at high amounts of P- and N-compounds. Samples
with a ratio of P+N-cpds/Polyester<0.3 for PET/PBT>55/45 show
no V0 rating (Reference samples #5, #6 and #7). Reference sample #8
versus #9 shows that an anti-dripping agent is needed for a V0
rating. Samples with a ratio of P+N-cpds/Polyester>0.6 for a
PET/PBT>55/45 show impact properties below 25 kJ/m2 (Reference
sample #12), in contrast with samples with a ratio <0.6. Samples
with a P-/N-compound ratio <0.8 also show bad impact (Reference
sample #5 versus #6, and #11 versus #9). To obtain a material with
good impact also a minimum molecular weight is needed; sample #14
is added as Reference.
1 #1 #2 #3 #4 #5 #6 #7 #8 #11 #12 #14 Ingredients (Ref) (Ref) (Ref)
(Ref) (Ref) (Ref) (Ref) (Ref) #9 #10 (Ref) (Ref) #13 (Ref) PBT
(Mw.about. 44.3 39.8 28 84,000) PET (Mw.about. 15 44.8 54.8 54.8
54.6 44.8 44.3 49.3 44.3 39.3 44.3 60,000) PET (Mw.about. 44.3
45,000) RDP 15 13 15 BPA-DP 15 5 10 10 15 15 10 10 15 15 X4PIP 15
Mel. Cyan. 10 15 13 10 10 5 5 10 10 10 15 15 10 10 TSAN 0.5 0.5 0.6
0.2 0.5 0.5 0.5 0.5 0.5 0.5 GF 30 30 30 30 30 30 30 30 30 30 30 30
30 30 Stab/Pigments 0.2 0.2 0.4 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2
0.2 0.2 P + N - 0.56 0.75 0.6 0.56 0.27 0.27 0.27 0.56 0.56 0.41
0.56 0.76 0.56 0.56 cpds/Polyester P-/N- compound 1.5 1 1 1.5 0.5 2
2 1.5 1.5 1 0.67 1 1.5 1.5 PET/PBT 0/100 0/100 35/65 100/0 100/0
100/0 100/0 100/0 100/0 100/0 100/0 100/0 100/0 Properties IUI
(kJ/m2) 44 37 32 32 25 36 38 33 30 33 21 21 26 17 UL @ 1.6 mm NC NC
V2 V2 V2 V2 V1/V2 V2 V0 V0 V0 V0 V0 V0 960 C GWT @ No pass No pass
Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass 1 mm
Color after 500 Dark Beige Dark Dark Beige Beige Beige Beige Beige
Beige Beige Beige Beige Beige hrs @ 150 C. Brown Brown Brown
[0060] While preferred embodiments have been shown and described,
various modifications and substitutions may be made thereto without
departing from the spirit and scope of the invention. Accordingly,
it is to be understood that the present invention has been
described by way of illustration and not limitations.
* * * * *