U.S. patent application number 12/694664 was filed with the patent office on 2010-05-27 for modified styrene-maleic acid copolymer and use thereof.
This patent application is currently assigned to International Center for Environ. Tech. Transfer. Invention is credited to Tetsuya Maekawa, Takaharu Nakagawa, Toyoyuki Urabe, Takeshi Yoshimura.
Application Number | 20100130694 12/694664 |
Document ID | / |
Family ID | 36497987 |
Filed Date | 2010-05-27 |
United States Patent
Application |
20100130694 |
Kind Code |
A1 |
Yoshimura; Takeshi ; et
al. |
May 27, 2010 |
MODIFIED STYRENE-MALEIC ACID COPOLYMER AND USE THEREOF
Abstract
The present invention relates to a modified styrene-maleic acid
copolymer obtained by reacting a carboxylic acid group in a
styrene-maleic acid copolymer with a halogen and/or epoxy compound.
The modified styrene-maleic acid copolymer is useful as a low
profile additive for a thermosetting resin, a water-absorbing
material, etc.
Inventors: |
Yoshimura; Takeshi;
(Moriguchi-shi, JP) ; Maekawa; Tetsuya;
(Amagasaki-shi, JP) ; Nakagawa; Takaharu;
(Ikoma-gun, JP) ; Urabe; Toyoyuki; (Ikeda-shi,
JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, L.L.P.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
International Center for Environ.
Tech. Transfer
Yokkaichi-Shi
JP
PANASONIC ELECTRIC WORKS CO., LTD.
Kadoma-shi
JP
|
Family ID: |
36497987 |
Appl. No.: |
12/694664 |
Filed: |
January 27, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11720201 |
May 25, 2007 |
|
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PCT/JP05/21464 |
Nov 22, 2005 |
|
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12694664 |
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Current U.S.
Class: |
525/329.5 |
Current CPC
Class: |
C08L 25/08 20130101;
C08F 8/02 20130101; C08J 11/14 20130101; Y02W 30/704 20150501; C08F
283/00 20130101; C08F 265/02 20130101; C08L 51/003 20130101; C08F
257/02 20130101; C08F 285/00 20130101; Y02W 30/62 20150501; C08F
8/08 20130101; C08L 67/06 20130101; C08L 51/003 20130101; C08L
2666/02 20130101; C08L 51/003 20130101; C08L 2666/14 20130101; C08F
8/44 20130101; C08F 222/08 20130101; C08F 212/08 20130101; C08F
8/44 20130101; C08F 212/08 20130101; C08F 222/08 20130101; C08F
8/08 20130101; C08F 8/44 20130101; C08F 212/08 20130101; C08F 8/08
20130101; C08F 8/44 20130101; C08F 222/08 20130101; C08F 8/02
20130101; C08F 8/44 20130101; C08F 222/08 20130101; C08F 8/02
20130101; C08F 8/44 20130101; C08F 212/08 20130101; C08L 51/003
20130101; C08L 2666/04 20130101; C08L 67/06 20130101; C08L 2666/06
20130101 |
Class at
Publication: |
525/329.5 |
International
Class: |
C08F 122/02 20060101
C08F122/02 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 25, 2004 |
JP |
2004-341135 |
Feb 23, 2005 |
JP |
2005-047998 |
Jul 26, 2005 |
JP |
2005-216377 |
Claims
1. A modified styrene-maleic acid copolymer, which is produced by a
process comprising reacting a carboxylic acid salt in a
styrene-maleic acid copolymer containing a structural unit
represented by the formula (1): ##STR00004## wherein A is a metal
element, m is a number from 1 to 3, n is a number from 3 to 300,
and both ends are hydrogen atoms, with the proviso that when A is a
di- or more valent metal element, the metal element may form a salt
with plural carboxy groups, which are not limited to those in the
same molecule, with a compound containing at least two
halogens.
2. The modified styrene-maleic acid copolymer according to claim 1,
wherein the compound containing at least two halogens is
1,3-dichloro-2-propanol.
3. The modified styrene-maleic acid copolymer according to claim 1,
which is produced by a process comprising reacting a carboxylic
acid salt in a styrene-maleic acid copolymer with a compound
containing at least two halogens such that the amount of the
halogen in the compound is 4/5 or less equivalent relative to the
amount of the carboxylic acid salt in the copolymer.
4. The modified styrene-maleic acid copolymer according to claim 1,
wherein the styrene-maleic acid copolymer to be modified is
produced by a process comprising decomposing a thermosetting resin
comprising a polyester and its crosslinking moiety with subcritical
water.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of and claims the
benefit of priority to U.S. Ser. No. 11/720,201, filed May 25,
2007, the entire contents of which are incorporated herein by
reference. U.S. Ser. No. 11/720,201 is a 371 of PCT/JP2005/21464,
filed Nov. 22, 2005, and was filed claiming the priority to the
Japanese Patent Application Nos. 2004-341135, filed Nov. 25, 2004,
2005-047998, filed Feb. 23, 2005, and 2005-216377, filed Jul. 26,
2005, the entire contents of which are herein incorporated by
reference.
TECHNICAL FIELD
[0002] The present invention relates to a modified styrene-maleic
acid copolymer based on a styrene-maleic acid copolymer, which is
obtained by decomposing a thermosetting resin and recovering the
decomposition product, and the use thereof.
BACKGROUND ART
[0003] Thermosetting resins such as fiber-reinforced plastics
(FRPs) have been widely used as a material for bathroom component
products such as a bathtub. Unlike thermoplastic resins,
thermosetting resins cannot be recycled by melting and remolding
them. In addition, the resins generally contain about 70% of
inorganic materials such as an inorganic filler, and therefore, the
self-combustion of the resins is difficult. Accordingly, most of
waste plastics such as FRPs based on thermosetting resins have been
dumped by reclaiming lands with the same, since they are very
difficult for recycling. However, this waste disposal by way of
reclaiming the lands has difficulties in the ensuring of sites to
be reclaimed and in stable hardening of such sites. To solve these
problems, the Containers and Packaging Recycling Law was instituted
in 1995 in Japan, so as to obligate the recovering and recycling of
plastics. This trend of recovering and recycling products
containing plastics is prevailing in association with the
enforcement of a variety of recycling laws.
[0004] Under these situations, recently, trials to recycle waste
plastics for use as a resource have been attempted. As one of such
trials, there is proposed a method of recovering useful oily
substances from waste plastics by decomposing the waste plastics
through a reaction using supercritical water as a reaction medium.
There is also proposed a method of recycling fiber-reinforced
plastics used in various structural materials, in which the plastic
components in such materials are decomposed by using supercritical
water or subcritical water, so as to recover fibers such as glass
fibers and carbon fibers for recycling them.
[0005] By these methods, plastics are decomposed into oily
components having lower molecular weights sc as to recycle these
components as liquid fuels. There is further proposed a method of
decomposing plastics, which makes use of a hydrolysis reaction by
high temperature water vapor. According to this method, it is
possible to decompose the organic polymer components of
thermoplastic and thermosetting plastics to some extents.
[0006] However, the above methods have a disadvantage in that,
since plastics are decomposed in random, the decomposition products
are oily materials comprising various components, and thus in that
it is difficult to obtain decomposition products with constant
qualities. Consequently, a post-treatment for reforming the oily
materials by using a catalyst, typically, zeolite, is needed, which
results in higher cost. Further, it is difficult to produce
petroleum products such as lamp oil and light oil from such
reformed oils, and therefore, such reformed oils have not yet been
put into practical use.
[0007] In the method described in the following Patent Literature
1, the decomposed resin is recycled as an unsaturated polyester
resin again. However, the method has problems that the re-cured
product of the decomposed resin has different properties from those
of the original thermosetting resin (i.e., the resin has lower
properties as a thermosetting resin), and the occupancy rate of the
decomposed resin in the re-cured product is limited to a low
extent, since the thermal decomposition of the decomposed resins is
occurred due to the high decomposition temperature.
[0008] Recently, there is proposed a method for decomposing a
thermosetting resin with subcritical water having a strong
hydrolysis ability. More specifically, the method comprises
hydrolyzing a thermosetting resin with subcritical water as a
reaction solvent, recovering the resultant low to middle molecular
weight compound, and reusing the compound as a raw material for a
resin (see, for example, the Patent Literature 2 and the like).
[0009] Patent Literature 1: JP-A-9-221565 (1997)
[0010] Patent Literature 2: JP-A-10-024274 (1998)
DISCLOSURE OF INVENTION
[0011] However, when a thermosetting resin is decomposed and
recovered the decomposition product as described above, the
recovered decomposition product as is cannot be reused.
Consequently, it is desired to modify the recovered decomposition
product to be reusable.
[0012] Under the above-discussed circumstances, the present
invention is accomplished, and an object of the present invention
is to provide a modified styrene-maleic acid copolymer, which is
reusable and is obtained by modifying a recovered decomposition
product of a thermosetting resin, and the use thereof.
MEANS FOR SOLVING THE PROBLEMS
[0013] The present invention includes the followings:
<1> A modified styrene-maleic acid copolymer, which is
obtained by reacting a carboxylic acid group in a styrene-maleic
acid copolymer with a halogen and/or epoxy compound. <2> The
modified styrene-maleic acid copolymer according to the
above-mentioned <1>, wherein the halogen and/or epoxy
compound is a halogen compound containing no unsaturated groups.
<3> The modified styrene-maleic acid copolymer according to
the above-mentioned <2>, wherein the halogen compound
containing no unsaturated groups is a compound selected from
epichlorohydrin, 1,3-dichloro-2-propanol, chlorobenzene, benzyl
chloride, a benzyl chloride compound having a substituent bound to
the benzene ring, and a halogenated alkyl. <4> The modified
styrene-maleic acid copolymer according to the above-mentioned
<2> or <3>, which is obtained by reacting a carboxylic
acid group in a styrene-maleic acid copolymer with a halogen
compound containing no unsaturated groups such that the amount of
the halogen in the compound is 4/5 or more equivalent relative to
the amount of the carboxylic acid group in the copolymer. <5>
The modified styrene-maleic acid copolymer according to the
above-mentioned <1>, wherein the halogen and/or epoxy
compound is a compound containing at least two halogens and/or
epoxy groups. <6> The modified styrene-maleic acid copolymer
according to the above-mentioned <5>, wherein the compound
containing at least two halogens and/or epoxy groups is a compound
selected from 1,3-dichloro-2-propanol, epichlorohydrin, and
1,4-butanediol diglycidyl ether. <7> The modified
styrene-maleic acid copolymer according to the above-mentioned
<5> or <6>, which is obtained by reacting a carboxylic
acid group in a styrene-maleic acid copolymer with a compound
containing at least two halogens and/or epoxy groups such that the
amount of the halogen and/or epoxy group in the compound is 4/5 or
less equivalent relative to the amount of the carboxylic acid group
in the copolymer. <8> The modified styrene-maleic acid
copolymer according to any one of the above-mentioned <1> to
<7>, wherein the styrene-maleic acid copolymer is obtained by
decomposing a thermosetting resin comprising a polyester and its
crosslinking moiety with subcritical water. <9> A process for
producing a modified styrene-maleic acid copolymer according to the
above-mentioned <1>, which comprises reacting a carboxylic
acid group in a styrene-maleic acid copolymer with a halogen and/or
epoxy compound. <10> An unsaturated polyester resin
composition comprising the modified styrene-maleic acid copolymer
according to any one of the above-mentioned <2> to <4>,
styrene, an unsaturated polyester resin, and a radical initiator.
<11> A low profile additive for a thermosetting resin
comprising the modified styrene-maleic acid copolymer according to
any one of the above-mentioned <2> to <4>. <12> A
water-absorbing material comprising the modified styrene-maleic
acid copolymer according to any one of the above-mentioned
<5> to <7>. <13> A process for recycling a
thermosetting resin, which comprises decomposing a thermosetting
resin comprising a polyester and its crosslinking moiety with
subcritical water to thereby obtain a styrene-maleic acid
copolymer, and reacting the carboxylic acid group in the
styrene-maleic acid copolymer with a halogen and/or epoxy compound
to thereby obtain a modified styrene-maleic acid copolymer.
EFFECT OF THE INVENTION
[0014] The modified styrene-maleic acid copolymer according to the
present invention is one obtained by modifying a carboxylic acid
group in a styrene-maleic acid copolymer with a halogen and/or
epoxy compound, and can be effectively utilized as a low profile
additive for a thermosetting resin, a water-absorbing material,
etc.
[0015] The unsaturated polyester resin composition according to the
present invention contains the above-mentioned modified
styrene-maleic acid copolymer as a low profile additive, and can be
molded without curing shrinkage.
[0016] The process for recycling a thermosetting resin according to
the present invention comprises decomposing a thermosetting resin,
recovering the resultant styrene-maleic acid copolymer, and
modifying the copolymer with a halogen and/or epoxy compound, and
can provide a method for recycling the copolymer as a low profile
additive for a thermosetting resin, a water-absorbing material,
etc.
BEST MODE FOR CARRYING OUT THE INVENTION
[0017] The styrene-maleic acid copolymer in the present invention
is a copolymer containing a structural unit represented by the
formula (1):
##STR00001##
[0018] wherein, A is a hydrogen atom or a metal element, m is a
number from 1 to 3, n is a number from 3 to 300, and both ends are
hydrogen atoms. In other words, the compound is a copolymer of
styrene with maleic acid (including a copolymer of styrene with
fumaric acid).
[0019] The metal element represented by A in the above-mentioned
formula (1) includes an alkaline metal such as lithium, sodium and
potassium; an alkaline earth metal such as calcium; and the like.
When the metal element represented by A is a di- or more valent
metal element (e.g., calcium), the metal element may form a salt
with plural carboxy groups, which are not limited to those in the
same molecule.
[0020] The above-mentioned styrene-maleic acid copolymer can be
obtained, for example, by hydrolyzing a thermosetting resin
comprising a polyester and its crosslinking moiety with subcritical
water.
[0021] Hereinafter, this method will be described, but the resin in
the present invention is not limited to the resin obtained by the
method.
[0022] The term "polyester" in the above-mentioned "thermosetting
resin comprising a polyester and its crosslinking moiety" referred
to means a polymer which is obtained by polycondensation of a
polyhydric alcohol component and a polybasic acid component so that
polyhydric alcohol residues and polybasic acid residues are linked
to each other through ester bonds. The polyester may contain a
double bond derived from, for example, an unsaturated polybasic
acid.
[0023] The term "crosslinking moiety" means a moiety which
crosslinks the molecules of the polyester. The crosslinking moiety
is, for example, a moiety derived from a crosslinking agent,
although not particularly limited thereto. The crosslinking moiety
may be a moiety derived from one molecule of crosslinking agent or
derived from an oligomer or a polymer (hereinafter collectively
referred to as a "polymer") formed by polymerizing a plurality of
crosslinking agents. Further, the position and manner of bonding
between the molecules and the polyester are not particularly
limited.
[0024] Accordingly, the "thermosetting resin comprising a polyester
and its crosslinking moiety" is a network thermosetting polymer (or
a network polyester resin) which is prepared by crosslinking a
polyester obtained from a polyhydric alcohol component and a
polybasic acid component, through a crosslinking moiety.
[0025] In this connection, the "thermosetting resin" to be used in
the present invention mainly means a resin which is cured (or
crosslinked) by heating or the like. However, the scope of the
resin according to the present invention includes an uncured or
partially cured resin of which the curing (or crosslinking) is
proceeding by heating or the like.
[0026] Examples of the polyhydric alcohol in the above-mentioned
"polyester" include, but not limited to, glycols such as ethylene
glycol, propylene glycol, diethylene glycol and dipropylene glycol.
Each of these glycols may be used in combination.
[0027] Examples of the polybasic acid include, but not limited to,
aliphatic unsaturated polybasic acids (e.g., aliphatic unsaturated
dibasic acids such as maleic anhydride, maleic acid and fumaric
acid). Each of the unsaturated polybasic acids may be used in
combination with a saturated polybasic acid such as phthalic
anhydride or the like.
[0028] Examples of the crosslinking agent in the above-mentioned
"crosslinking moiety" include, but not limited to, polymerizable
vinyl monomers such as styrene and methyl methacrylate.
[0029] The thermosetting resin comprising a polyester and its
crosslinking moiety which is a raw material for the styrene-maleic
acid copolymer in the present invention is not particularly
limited, as long as the styrene-maleic acid copolymer can be caused
by the decomposition of the resin. Examples thereof include a
thermosetting resin comprising a polyester containing a maleic acid
residue (including fumaric acid residue) and its crosslinking
moiety which is based on styrene and is bound to the maleic acid
residue, which is obtained by using an acid for forming the maleic
acid residue (e.g., maleic anhydride, maleic acid, and fumaric
acid) as a polybasic acid for forming a polyester, and styrene as a
crosslinking agent for forming a crosslinking moiety. The
thermosetting resin may be of any type, in so far as the
above-mentioned styrene-maleic acid copolymer can be obtained from
the resin. In other words, there is no limit in selection of the
type, structure and components of the resin, the type, amount and
crosslinking degree of the crosslinking moiety (or a crosslinking
agent), and the types and amounts of additives. For example, wastes
from bathroom components, such as fiber-reinforced plastics (FRP)
and the like, are also used as a raw material.
[0030] The above-mentioned hydrolysis reaction of the thermosetting
resin with subcritical water is carried out by adding water to the
thermosetting resin, and then increasing the temperature and
pressure of water to thereby put the water in a subcritical state.
The ratio of the thermosetting resin to water is not particularly
limited. Preferably, 100 to 500 parts by weight of water is added
to 100 parts by weight of the thermosetting resin.
[0031] The "subcritical water" referred to in the present invention
means water in such a state that the temperature and pressure of
the water are within the following ranges, respectively: the
temperature and the pressure of water are not higher than the
critical points of water (critical temperature: 374.4.degree. C.,
and critical pressure: 22.1 MPa), provided that the temperature of
the water is concurrently not lower than 140.degree. C., and
provided that the pressure of the water is concurrently not lower
than 0.36 MPa (i.e., a saturated vapor pressure at 140.degree.
C.)
[0032] The temperature of the subcritical water in the reaction is
lower than the thermal decomposition temperature of the
thermosetting resin. The lower limit of the temperature of the
subcritical water is preferably 180.degree. C., and more preferably
200.degree. C., and the upper limit thereof is preferably
280.degree. C., and more preferably 270.degree. C. When the
temperature of the subcritical water is lower than the above lower
limit during the decomposition reaction, a very long time is
required to decompose the thermosetting resin, which may lead to a
higher cost. On the other hand, when the temperature of the
subcritical water is higher than the above upper limit during the
decomposition reaction, the styrene-maleic acid copolymer is also
decomposed, which makes it hard to recover the copolymer.
[0033] The thermal decomposition temperature of the thermosetting
resin means a temperature which corresponds to the intersection
point of a tangent drawn at a bending point of the decomposition
steps of a resin component on a chart obtained by the
thermogravimetric analysis (or TG analysis) of a resin sample, with
a zero horizontal line of the TG curve.
[0034] The time for the treatment with the subcritical water
changes depending on the conditions such as the reaction
temperature, etc. For example, the time is from about 1 to about 12
hours, and preferably from about 1 to about 4 hours. The better,
the shorter the time is, since the cost for the treatment is
reduced. The pressure during the decomposition reaction (the
treatment with subcritical water) changes depending on the
conditions such as the reaction temperature, etc. The lower limit
thereof is preferably 1 MPa, and more preferably 2 MPa, and the
upper limit thereof is preferably 15 MPa, and more preferably 7
MPa.
[0035] It is preferable in the above-mentioned reaction that
subcritical water contains an alkaline salt. The alkaline salt in
subcritical water accelerates the hydrolysis reaction of the
thermosetting resin, so that the treating time and cost can be
saved. When the thermosetting resin is treated with subcritical
water within a high temperature range close to a supercritical
state, a polyhydric alcohol as one of the decomposition products
may be subjected to a secondary decomposition due to the acid
catalytic effect of an organic acid which is concurrently produced.
When an alkaline salt is contained in subcritical water, the base
of the alkaline salt can neutralize the organic acid to thereby
inhibit the above secondary decomposition of the polyhydric
alcohol.
[0036] The term "alkaline salt" means a salt of an alkaline metal
or a salt of an alkaline earth metal, which reacts with an acid to
show basic properties. Examples of the alkaline salt include, but
not limited to, the hydroxides of alkaline metals such as potassium
hydroxide (KOH), sodium hydroxide (NaOH), etc., calcium carbonate,
barium carbonate, calcium hydroxide, magnesium carbonate, etc.,
among which the hydroxides of the alkaline metals are particularly
preferable.
[0037] Although not particularly limited, the content of the
alkaline salt in subcritical water is preferably not less than 2
molar equivalents relative to the theoretical number of moles of an
acid residue (or a maleic acid residue) contained in the
above-mentioned styrene-maleic acid copolymer, which is obtained by
decomposing the thermosetting resin. When the content of the
alkaline salt is less than 2 molar equivalents, it may become hard
to recover the above resin. While not limited to, the upper limit
of the content of the alkaline salt in subcritical water is
preferably not more than 10 molar equivalents in view of cost.
[0038] The "theoretical number of moles of an acid residue
contained in a styrene-maleic acid copolymer" means an estimated
number of moles of the acid residue (or the maleic acid residue) in
the compound obtained through the decomposition calculated from a
ratio of the number of the molecules of the acid residue and the
number of the molecules of the residue derived from the
crosslinking moiety, obtained by the NMR analysis of the compound,
and from the amount of the crosslinking moiety-forming material
used.
[0039] The concentration of the alkaline salt in the subcritical
water is generally not less than 0.2 mol/L.
[0040] When the above-mentioned thermosetting resin is thus
subjected to the hydrolysis with the subcritical water as a
reaction solvent, preferably in the presence of the alkaline salt,
the ester bonds of the polyester are hydrolyzed, whereas the
binding sites between a maleic acid residue and a crosslinking
moiety based on styrene are not hydrolyzed. As a result, the
styrene-maleic acid copolymer can be obtained as a decomposition
product.
[0041] The modified styrene-maleic acid copolymer according to the
present invention can be obtained by reacting at least a part of
the carboxylic acid groups in the above-mentioned styrene-maleic
acid copolymer with a halogen and/or epoxy compound containing a
halogen and/or epoxy group as a modifying agent (see the following
formulas (2) and (3)).
[0042] The "carboxylic acid group" means a carboxy group or a salt
thereof in a maleic acid structure moiety (maleic acid unit) in the
above-mentioned styrene-maleic acid copolymer, which corresponds to
the --COOA moiety in the above-mentioned formula (1).
[0043] The "part" means that all of the carboxylic acid groups in
the above-mentioned styrene-maleic acid copolymer do not
necessarily have to be modified, and a part of carboxylic acid
groups may be modified.
[0044] The following formula (2) shows a reaction of the
above-mentioned styrene-maleic acid copolymer with a halogen
compound (corresponding to the R--X in the formula (2), wherein X
is a halogen, and R is a group other than a halogen). The modified
styrene-maleic acid copolymer can be obtained by the substitution
reaction of the carboxylic acid group moiety in the maleic acid
structure moiety with the halogen compound. The formula (2) shows a
reaction scheme wherein the halogen compound is used in 0.5
equivalent relative to the carbonate in the maleic acid structure
moiety.
##STR00002##
[0045] The following formula (3) shows a reaction of the carboxylic
acid group in the styrene-maleic acid copolymer (when A is a
hydrogen atom in the formula (1)) with a compound containing an
epoxy group (corresponding to R--CH.sub.2--(--O--)--CH.sub.2 in the
formula (3), wherein R is a group other than an epoxy group). In
this case, a hydrophilic group (hydroxy group) is also contained in
a connection part, which is a part derived from an epoxy group,
between the group R and the resin, so that a modified
styrene-maleic acid copolymer having superior water-absorbing
property can be obtained.
##STR00003##
[0046] The above-mentioned halogen and/or epoxy compound used as a
modifying agent for the styrene-maleic acid copolymer in the
present invention is a compound containing at least one halogen
and/or epoxy group. Examples thereof include a compound (halogen
compound) containing at least one halogen, a compound (epoxy
compound) containing at least one epoxy group, and a compound
containing at least one halogen and at least one epoxy group, which
is belong to both of the halogen compound and the epoxy compound.
In the present invention, two or more of these compounds may be
used in combination.
[0047] The "halogen" in the above-mentioned compound includes a
fluorine atom, a chlorine atom, a bromine atom, an iodine atom and
the like. It is preferable to use a chlorine atom, a bromine atom,
or an iodine atom, since these atoms show a superior effect as a
leaving group.
[0048] The above-mentioned halogen compound includes not only a
compound containing at least one halogen, but also a compound
containing two or more halogens. Examples of the compound include
1,3-dichloro-2-propanol, chlorobenzene, benzyl chloride, a benzyl
chloride compound having a substituent bound to the benzene ring, a
halogenated alkyl and the like.
[0049] The benzyl chloride compound having a substituent bound to
the benzene ring includes methylbenzyl chloride, nitrobenzyl
chloride and the like.
[0050] The halogenated alkyl is represented by the general formula:
C.sub.nH.sub.2n+1X, wherein X is a fluorine atom, a chlorine atom,
a bromine atom, or an iodine atom. Examples thereof include methyl
iodide, propyl bromide, isopropyl bromide and the like.
[0051] The above-mentioned epoxy compound includes not only a
compound containing at least one epoxy group, but also a compound
containing two or more epoxy groups. Examples of the compound
include a compound containing a glycidyl group, a compound
containing a glycidyl ether group and the like. Specific examples
thereof include 1,4-butanediol diglycidyl ether, styrene oxide
(1,2-epoxybenzene), phenyl glycidyl ether,
glycidol(2,3-epoxy-1-propanol) and the like.
[0052] The above-mentioned compound containing at least one halogen
and at least one epoxy group also includes a compound containing
two or more halogens and two or more epoxy groups (e.g., a glycidyl
group or a glycidyl ether group). Examples of the compound include
epichlorohydrin and the like.
[0053] In particular, when the modified styrene-maleic acid
copolymer according to the present invention is used as a low
profile additive for a thermosetting resin as described below, it
is preferable to use a halogen compound containing no unsaturated
groups as a halogen and/or epoxy compound. This is based on the
following speculations: when a compound having an unsaturated group
is used as a modifying agent, the polymerization reaction of
compounds having an unsaturated group may proceed more rapidly than
the modification reaction of the styrene-maleic acid copolymer, so
that the modification of the resultant modified copolymer may be
insufficient and the low profile ability of the resultant modified
copolymer may be reduced. In addition, the polymer of compounds
having an unsaturated group may be reacted with the styrene-maleic
acid copolymer, so that the reaction solution may be clouded due to
the formation of the high-molecular-weight product and the low
profile ability of the resultant modified copolymer may be
reduced.
[0054] Examples of the halogen compound containing no unsaturated
groups include epichlorohydrin, 1,3-dichloro-2-propanol,
chlorobenzene, benzyl chloride, a benzyl chloride compound having a
substituent bound to the benzene ring, a halogenated alkyl and the
like.
[0055] In particular, when the modified styrene-maleic acid
copolymer according to the present invention is used as a
water-absorbing resin as described below, it is preferable to use a
compound containing at least two halogens and/or epoxy groups,
i.e., a compound containing at least two halogens, a compound
containing at least one halogen and at least one epoxy group, and a
compound containing at least two epoxy groups, as a halogen and/or
epoxy compound. In this case, a crosslinking structure via a
residue of the compound may be formed intermolecular or between the
different molecules of the styrene-fumarate molecule forming the
styrene-maleic acid copolymer.
[0056] Preferred examples of the compound containing at least two
halogens include 1,3-dichloro-2-propanol. This propanol is
water-soluble, and can be easily reacted with the styrene-maleic
acid copolymer. In other words, the styrene-maleic acid copolymer
can be modified into a resin showing a superior water-absorbing
property by using the compound in relatively mild conditions.
[0057] Preferred examples of the compound containing at least one
halogen and at least one epoxy group include epichlorohydrin and
the like. In the case of using epichlorohydrin, the resultant
modified styrene-maleic acid copolymer may have a crosslinking
structure containing a hydrophilic group, so that the modified
copolymer may become a resin showing a superior water-absorbing
property.
[0058] Preferred examples of the compound containing at least two
epoxy groups include 1,4-butanediol diglycidyl ether and the like.
Although this ether is hardly soluble in water and has a poor
reactivity to the styrene-maleic acid copolymer, the resultant
modified styrene-maleic acid copolymer may have a crosslinking
structure containing a lot of hydrophilic groups, so that the
modified copolymer can be utilized as a polymer having a relatively
high molecular weight, and showing a high water-absorbing property
and a heat resistance.
[0059] The amount of the halogen and/or epoxy compound to be
reacted with the styrene-maleic acid copolymer is not particularly
limited. Also, the reaction temperature, the reaction time and the
like are not particularly limited. Accordingly, these can be
changed in accordance with the desired properties of the resultant
modified styrene-maleic acid copolymer.
[0060] For example, when a modified styrene-maleic acid copolymer,
which is suitable as a low profile additive for reducing a curing
shrinkage of a thermosetting resin, is produced by using a halogen
compound containing no unsaturated groups, it is preferable to
adjust the amount of the halogen in the halogen compound to be 4/5
or more equivalent relative to 1 equivalent of the carboxylic acid
group in the styrene-maleic acid copolymer. When the amount of the
halogen in the compound is less than 4/5 equivalent relative to the
amount of the carboxylic acid group in the styrene-maleic acid
copolymer, the amount of the group having no unsaturated groups to
be incorporated into the styrene-maleic acid copolymer may be
insufficient, so that when the resultant copolymer is used as a low
profile additive, the low profile effect cannot be sufficiently
obtained. The upper limit of the amount of the compound to be
reacted is not particularly limited. Further reaction does not
occur even if the compound is used such that the amount of the
halogen and/or epoxy group in the compound is more than 1
equivalent relative to 1 equivalent of the carboxylic acid group in
the styrene-maleic acid copolymer. In this regard, it may be
possible that the compound is added such that the amount is about 3
times equivalents, and then, the excessive amounts of the compound
is recovered after the reaction, in order to accelerate the
reaction rate.
[0061] In this case, the reaction of the carboxylic acid group in
the styrene-maleic acid copolymer with the halogen compound
containing no unsaturated groups is carried out at a temperature of
preferably 100.degree. C. or less, and more preferably 80.degree.
C. or less. When the reaction temperature exceeds 100.degree. C.,
side reactions may be caused. The lower limit of the reaction
temperature is not particularly limited, but is preferably
40.degree. C. or more in order to ensure the reaction rate. The
reaction time is not particularly limited, but is preferably within
a range of 2 to 10 hours.
[0062] In this case, it is preferable to react the carboxylic acid
group in the styrene-maleic acid copolymer with the halogen
compound containing no unsaturated groups in the presence of a
phase-transfer catalyst. Examples of the phase-transfer catalyst
include a quaternary ammonium salt such as tetra-n-butylammonium
bromide ([CH.sub.3(CH.sub.2).sub.3].sub.4N.Br). For example, the
reaction of the carboxylic acid group with the halogen compound
containing no unsaturated groups may be effectively progressed by
using tetra-n-butylammonium bromide
([CH.sub.3(CH.sub.2).sub.3].sub.4N.Br) as a phase-transfer catalyst
in a water-toluene phase.
[0063] In addition, for example, when a modified styrene-maleic
acid copolymer having a high water-absorbing property is produced
by using a compound containing at least two halogens and/or epoxy
groups, it is preferable to mix and react the compound containing
at least two halogens and/or epoxy groups with the styrene-maleic
acid copolymer such that the amount of the halogen and/or epoxy
group in the compound is 4/5 or less equivalent relative to the
amount of the carboxylic acid group in the copolymer. In this case,
a modified resin containing a crosslinking structure containing a
hydrophilic group can be reproducibly obtained. When the amount of
the halogen and/or epoxy group is more than 4/5 equivalent relative
to the carboxylic acid group in the styrene-maleic acid copolymer,
a modified styrene-maleic acid copolymer having a high
water-absorbing property may not be obtained. The lower limit of
the equivalent of the halogen and/or epoxy group relative to the
carboxylic acid group in the styrene-maleic acid copolymer is not
particularly limited. It is preferable to mix the compound
containing at least two halogens and/or epoxy groups with the
styrene-maleic acid copolymer such that the halogen and/or epoxy
group in the compound is 1/5 or more equivalent relative to the
carboxylic acid group in the copolymer in order to obtain a
modified styrene-maleic acid copolymer having a high
water-absorbing property.
[0064] In this case, the reaction temperature and the reaction time
can be appropriately adjusted depending on the kind of the
styrene-maleic acid copolymer or the compound containing at least
two halogens and/or epoxy groups to be used, and the like. For
example, the temperature can be set within a range of 30 to
120.degree. C., and the reaction time can be set within a range of
1 to 10 hours.
[0065] The modification rate of the carboxylic acid group in the
modified styrene-maleic acid copolymer obtained as described above
can be varied depending on the kind and the amount of the halogen
and/or epoxy compound to be used, reaction conditions, and the
like.
[0066] When the modified styrene-maleic acid copolymer is used as a
low profile additive for a thermosetting resin, the higher the
modification rate is, the more preferable it is. It is preferably
70 to 100 mol %, and more preferably 80 to 100 mol %. When the
modification rate is too low, the reducing effect on the curing
shrinkage may be insufficient.
[0067] In addition, when the modified styrene-maleic acid copolymer
is used as a water-absorbing material, the modification rate is
preferably 2 to 70 mol %, and more preferably 5 to 50 mol %. When
it violates either the lower limit or the upper limit, the
water-absorbing property may be insufficient.
[0068] The modified styrene-maleic acid copolymer according to the
present invention can reduce a curing shrinkage of a thermosetting
resin, so that it can be effectively used as a low profile additive
for a thermosetting resin. The modified resin has a water-absorbing
property, so that it can be effectively used as a water-absorbing
material.
[0069] The modified styrene-maleic acid copolymer according to the
present invention, in particular, the resin modified with the
halogen compound containing no unsaturated groups, has a superior
reducing effect on a curing shrinkage of a thermosetting resin, so
that it is useful as a low profile additive for a thermosetting
resin (in particular, an unsaturated polyester resin). Accordingly,
a low profile unsaturated polyester resin composition can be
prepared by mixing the modified styrene-maleic acid copolymer
according to the present invention, styrene, an unsaturated
polyester resin, and a radical initiator, and optionally an
inorganic filler such as calcium carbonate and other
components.
[0070] Examples of the unsaturated polyester resin used in the
above-mentioned resin composition include known unsaturated
polyester resins such as those obtained by binding a polyhydric
alcohol such as glycols (e.g., ethylene glycol, propylene glycol,
diethylene glycol, and dipropylene glycol) to an unsaturated
polybasic acid such as an aliphatic unsaturated dibasic acid (e.g.,
maleic anhydride, maleic acid, and fumaric acid) via an ester bond.
The unsaturated polyester resin may also be a virgin thermosetting
resin, or a resin prepared from monomers (i.e. a polyhydric alcohol
and an unsaturated polybasic acid) obtained by hydrolyzing a
thermosetting resin comprising an unsaturated polyester resin.
[0071] As a radical initiator used in the above-mentioned resin
composition, those which is generally used for a unsaturated
polyester resin can be used. Examples thereof include, but not
limited to, methyl ethyl ketone peroxide, benzoyl peroxide,
1,1-di(t-butylperoxy)butane, di(4-t-butylcyclohexyl)peroxy
dicarbonate and the like.
[0072] The amount of the modified styrene-maleic acid copolymer to
be added into the above-mentioned resin composition is preferably
within a range of 0.1 to 10% by weight, more preferably 1 to 10% by
weight, relative to the total amount of the resin composition. When
the amount of the modified styrene-maleic acid copolymer to be
added is less than 0.1% by weight, the reducing effect on the
curing shrinkage may not be sufficiently obtained, whereas when the
amount of the modified styrene-maleic acid copolymer to be added is
more than 10% by weight, a problem such as a deterioration of
solvent resistance may be caused.
[0073] The amount of the unsaturated polyester to be added into the
above-mentioned resin composition is preferably within a range of
10 to 50% by weight, more preferably 35 to 50% by weight, relative
to the total amount of the unsaturated polyester resin
composition.
[0074] The amount of styrene to be added is preferably within a
range of 7 to 50% by weight, and more preferably 35 to 50% by
weight, relative to the total amount of the unsaturated polyester
resin composition.
[0075] The amount of the radical initiator to be added is
preferably within a range of 0.5 to 2% by weight relative to the
total amount of the unsaturated polyester resin composition. When
the amount of the radical initiator to be added is less than 0.5%
by weight, the reaction rate is slowed down, whereas when the
amount exceeds 2% by weight, the reaction rate is too fast to
control.
[0076] In addition, the amount of other components (e.g., an
inorganic filler) to be optionally added into the above-mentioned
unsaturated polyester resin composition is, for example, within a
range of 0 to 70% by weight relative to the total amount of the
resin composition, although not particularly limited thereto.
[0077] A molded article can be produced by molding the thus
prepared unsaturated polyester resin composition according to any
of methods such as injection-molding, transfer molding, compression
molding and the like.
[0078] A sheet molding compound can be produced by impregnating a
fiber mat with the unsaturated polyester resin composition prepared
as described above. Any type of fiber mats such as glass fiber mat
can be used as a fiber mat. The sheet molding compound can be
produced, for example, by providing the unsaturated polyester resin
onto a fiber mat, which is obtained by accumulating a chopped
strand of glass fiber roving, in uniform thickness, and then,
inserting the resultant mat between two support films to thereby
form a sheet. This sheet molding compound can be set into a mold
and subjected to heat/pressure molding to thereby produce a
fiber-reinforced plastic (FRP) used as a bathroom component product
such as a bathtub and a waterproof pan for bathroom.
[0079] The present invention also provides a process for recycling
a thermosetting resin, which comprises
(1) decomposing a thermosetting resin comprising a polyester and
its crosslinking moiety with subcritical water to thereby obtain a
styrene-maleic acid copolymer, and (2) reacting the carboxylic acid
group in the styrene-maleic acid copolymer with a halogen and/or
epoxy compound to thereby obtain a modified styrene-maleic acid
copolymer.
[0080] In other words, the process provides a way for recycling a
decomposition product (a styrene-maleic acid copolymer) obtained by
decomposing a thermosetting resin with subcritical water and
recovering the decomposition product.
[0081] Preferably, the process further comprises
(3) providing an unsaturated polyester resin composition comprising
the modified styrene-maleic acid copolymer, styrene, an unsaturated
polyester resin, and a radical initiator, and (4) molding the
unsaturated polyester resin composition.
[0082] The above-mentioned step (2) preferably comprises reacting
the carboxylic acid group in the styrene-maleic acid copolymer with
a halogen and/or epoxy compound such that the amount of the halogen
and/or epoxy group in the compound is 4/5 or more equivalent
relative to the amount of the carboxylic acid group in the
copolymer, preferably at a temperature of 80.degree. C. or less, to
thereby obtain a modified styrene-maleic acid copolymer.
EXAMPLES
[0083] The present invention will be described in more detail below
by way of Examples thereof. The evaluation methods for the
properties of the resins used in Examples will be described
below.
<Evaluation of Properties>
(Modification Rate)
[0084] The modification rate of the carboxylic acid group was
calculated from the peak (1610 to 1550 cm.sup.-1) strength of
carboxylate and the peak (1770 to 1720 cm.sup.-1) strength of ester
generated after the reaction, which were measured by an infrared
spectroscopic analysis.
(Shrinkage Rate)
[0085] The shrinkage rate was determined by measuring a dimensional
change after the unsaturated polyester resin composition was poured
into a mold (100 mm.times.100 mm) and cured.
(Reaction Rate)
[0086] The cured molded article was immersed in a hot water at
100.degree. C. for 5 hours (hot water reflux extraction). The
reaction rate was calculated from the amount of an unreacted
material extracted with a hot water, which was represented as "hot
water extraction".
(Flexural Modulus and Flexural Strength)
[0087] The flexural modulus and the flexural strength were
determined according to JIS-K7017 under the following conditions:
test piece dimensions: 2 mm thickness.times.12 mm width.times.80 mm
length; distance between points of support: 50 mm; the test speed:
2 mm/min. The strengths with the displacements of an indenter at
the center of the test piece were measured. The flexural modulus
was determined based on the linear relationship between the
displacement and the strength, and the flexural strength was
determined from the strength at the yield point.
(Izod Impact Strength)
[0088] The izod impact strength test was performed by using a test
piece (dimensions: 2 mm thickness.times.12 mm width.times.80 mm
length), according to JIS-K7062. The izod impact strength was
determined by fixing one side of the test piece, hitting the test
piece with a hammer and measuring the energy needed to fracture the
test piece.
(Amount of Water Absorption)
[0089] The evaluation method for the amount of water absorption was
performed according to "Testing method for water absorption
capacity of super absorbent polymers" described in JIS-K7223. The
procedure of the method is outlined below.
[0090] This test was performed by using deionized water. Each
sample (about 0.20 g) is taken and weighed (a (g)). The weighed
sample is charged into the bottom of a tea bag, and the tea bag is
immersed in deionized water contained in a 1 L beaker. The
immersion time was set to 3 hours. After 3 hours, the tea bag is
taken up from the water and sufficiently drained, and the weight (b
(g)) of the tea bag is measured. On the other hand, a tea bag
containing no sample is immersed for the same immersion time and
drained, and the weight (c (g)) of the tea bag is measured.
[0091] The same procedure was repeated three times, and the average
value was calculated. The amount of water absorption W (g/g) was
calculated according to the following equation (1):
W(g/g)=(b-c-a)/a (1)
Example A
Example A1
[0092] An unsaturated polyester varnish (solvent free) having a
weight-average molecular weight of 4000 to 5000 was synthesized by
the condensation polymerization of propylene glycol as a glycol
with maleic anhydride as an unsaturated dibasic acid in equimolar
amounts. Then, the resultant unsaturated polyester, styrene, methyl
ethyl ketone peroxide as a radical initiator, and calcium carbonate
as an inorganic filler were mixed in a weight ratio of the
unsaturated polyester:styrene:methyl ethyl ketone peroxide:calcium
carbonate=1:1:0.02:2, and the mixture was cured. The cured product
was used as an unsaturated polyester resin to be decomposed and
recovered.
[0093] Next, the cured product (3 g) of the unsaturated polyester
resin, purified water (15 g), and KOH (0.84 g) were charged into a
reaction tube, and the internal atmosphere of the reaction tube was
replaced with an argon gas. Then, this reaction tube was
tightly-sealed and immersed in a constant temperature bath at a
temperature of 230.degree. C., to thereby put the water in the
reaction tube into a subcritical state and decompose the cured
product for 4 hours. After that, the contents in the reaction tube
were separated by filtration into an inorganic material and an
aqueous solution. Next, the aqueous solution was adjusted with
hydrochloric acid to an acidic region of pH 4 or less, to thereby
form a precipitate of a water-soluble component contained in the
aqueous solution. Then, the precipitate was recovered by filtration
to obtain a styrene-maleic acid copolymer.
[0094] Next, the styrene-maleic acid copolymer (15 g) obtained from
the above-mentioned method was dissolved into an alkaline water
obtained by dissolving potassium hydroxide (5.2 g) in water (79.8
g). Then, to this aqueous solution (100 g) of the potassium salt of
the styrene-maleic acid copolymer were added toluene (100 g) and
tetra-n-butylammonium bromide (1 g) as a phase-transfer catalyst,
and the mixture was stirred for 5 minutes. To this was further
added epichlorohydrin (7 g) as a halogen and/or epoxy compound, and
the mixture was reacted at 50.degree. C. for 5 hours. After that,
the reaction product was separated into a water phase and an
organic phase by using a separation funnel. By removing toluene
from the organic phase, a modified styrene-maleic acid copolymer
containing maleic acid structure moieties into which groups having
no unsaturated groups were incorporated was obtained as a white
powder (16 g; modification rate 80 mol %).
[0095] Next, the above-mentioned unsaturated polyester resin
varnish (solvent free) having a weight-average molecular weight of
4000 to 5000, styrene, methyl ethyl ketone peroxide as a radical
initiator, and calcium carbonate as an inorganic filler were mixed
in a weight ratio of the unsaturated polyester:styrene:methyl ethyl
ketone peroxide:calcium carbonate=1:1:0.02:2. Then, the
above-mentioned modified styrene-maleic acid copolymer was further
mixed to the mixture, such that the amount of the modified
copolymer was 10% by weight based on the total amount of the
composition, to thereby prepare an unsaturated polyester resin
composition.
Example A2
[0096] A modified styrene-maleic acid copolymer containing maleic
acid structure moieties into which groups having no unsaturated
groups were incorporated was obtained as a white powder (19 g;
modification rate 83 mol %) in the same manner as in Example A1,
except that 1,3-dichloro-2-propanol (10 g) was mixed as a halogen
and/or epoxy compound instead of epichlorohydrin (7 g), and the
reaction was carried out at 80.degree. C. for 5 hours. After that,
an unsaturated polyester resin composition was prepared by using
this modified styrene-maleic acid copolymer in the same manner as
in Example A1.
Example A3
[0097] A modified styrene-maleic acid copolymer containing maleic
acid structure moieties into which groups having no unsaturated
groups were incorporated was obtained as a white powder (17.5 g;
modification rate 85 mol %) in the same manner as in Example A1,
except that chlorobenzene (9 g) was mixed as a halogen and/or epoxy
compound instead of epichlorohydrin (7 g), and the reaction was
carried out at 60.degree. C. for 5 hours. After that, an
unsaturated polyester resin composition was prepared by using this
modified styrene-maleic acid copolymer in the same manner as in
Example A1.
Example A4
[0098] A modified styrene-maleic acid copolymer containing maleic
acid structure moieties into which groups having no unsaturated
groups were incorporated was obtained as a white powder (18.5 g;
modification rate 93 mol %) in the same manner as in Example A1,
except that tetra-n-butylammonium bromide (7 g) was mixed as a
phase-transfer catalyst, and benzyl chloride (28 g) was mixed as a
halogen and/or epoxy compound instead of epichlorohydrin (7 g), and
the reaction was carried out at 80.degree. C. for 10 hours. After
that, an unsaturated polyester resin composition was prepared by
using this modified styrene-maleic acid copolymer in the same
manner as in Example A1.
Example A5
[0099] A modified styrene-maleic acid copolymer containing maleic
acid structure moieties into which groups having no unsaturated
groups were incorporated was obtained as a white powder (19.5 g;
modification rate 95 mol %) in the same manner as in Example A1,
except that tetra-n-butylammonium bromide (7 g) was mixed as a
phase-transfer catalyst, and methylbenzyl chloride (32 g) was mixed
as a halogen and/or epoxy compound instead of epichlorohydrin (7
g), and the reaction was carried out at 70.degree. C. for 10 hours.
After that, an unsaturated polyester resin composition was prepared
by using this modified styrene-maleic acid copolymer in the same
manner as in Example A1.
Example A6
[0100] A modified styrene-maleic acid copolymer containing maleic
acid structure moieties into which groups having no unsaturated
groups were incorporated was obtained as a white powder (22 g;
modification rate 100 mol %) in the same manner as in Example A1,
except that tetra-n-butylammonium bromide (7 g) was mixed as a
phase-transfer catalyst, and nitrobenzyl chloride (39 g) was mixed
as a halogen and/or epoxy compound instead of epichlorohydrin (7
g), and the reaction was carried out at 80.degree. C. for 10 hours.
After that, an unsaturated polyester resin composition was prepared
by using this modified styrene-maleic acid copolymer in the same
manner as in Example A1.
Example A7
[0101] A modified styrene-maleic acid copolymer containing maleic
acid structure moieties into which groups having no unsaturated
groups were incorporated was obtained as a white powder (15 g;
modification rate 70 mol %) in the same manner as in Example A1,
except that tetra-n-butylammonium bromide (2.5 g) was mixed as a
phase-transfer catalyst, and propyl bromide (9.2 g) was mixed as a
halogen and/or epoxy compound instead of epichlorohydrin (7 g), and
the reaction was carried out at 70.degree. C. for 22 hours. After
that, an unsaturated polyester resin composition was prepared by
using this modified styrene-maleic acid copolymer in the same
manner as in Example A1.
Example A8
[0102] A modified styrene-maleic acid copolymer containing maleic
acid structure moieties into which groups having no unsaturated
groups were incorporated was obtained as a white powder (18.7 g;
modification rate 100 mol %) in the same manner as in Example A1,
except that tetra-n-butylammonium bromide (7 g) was mixed as a
phase-transfer catalyst, and benzyl chloride (28 g) was mixed as a
halogen and/or epoxy compound instead of epichlorohydrin (7 g), and
the reaction was carried out at 100.degree. C. for 6 hours. After
that, an unsaturated polyester resin composition was prepared by
using this modified styrene-maleic acid copolymer in the same
manner as in Example A1.
Comparative Example A1
[0103] In the same manner as in Example A1, the cured product of
the unsaturated polyester resin was decomposed with subcritical
water in the presence of KOH to thereby recover a styrene-maleic
acid copolymer. After that, an unsaturated polyester resin
composition was prepared by using this styrene-maleic acid
copolymer without the modification in the same manner as in Example
A1.
[0104] The unsaturated polyester resin compositions obtained in
Examples A1 to A8 and Comparative Example A1 were cured at room
temperature for 1 hour, followed by at 100.degree. C. for 2 hours
with heating, to thereby obtain the molded articles of Example A1
to A8 and Comparative Example A1.
[0105] For the purpose of comparison, the above-mentioned
unsaturated polyester resin varnish having a weight-average
molecular weight of 4000 to 5000, styrene, methyl ethyl ketone
peroxide as a radical initiator, and calcium carbonate as an
inorganic filler were mixed in a weight ratio of the unsaturated
polyester resin:styrene:methyl ethyl ketone peroxide:calcium
carbonate=1:1:0.02:2 to thereby obtain a virgin unsaturated
polyester resin composition, and the composition was molded in the
same manner as described above to thereby obtain a control molded
article.
[0106] For each of the cured molded articles of the control,
Example A1 to A8 and Comparative Example A1, the appearance was
observed, and the shrinkage rate, the flexural modulus, the
flexural strength and the Izod impact were determined. In addition,
the reaction rate was determined for each of the articles of
Example A4 to A8, control and Comparative Example A1. The results
are shown in Table 1.
TABLE-US-00001 TABLE 1 Ex. Ex. Ex. Ex. Ex. Ex. Ex. Ex. Com. Ex.
Cont. A1 A2 A3 A4 A5 A6 A7 A8 A1 Appearance No problems Many
evaluation bumps Reaction 99.3 -- -- -- 99.8 99.6 99.7 99.7 99.8 90
rate (%) Hot water extraction Shrinkage 4 0 0 0 0 0 0 0 0 4 rate
(%) Flexural 6700 6800 6900 6700 7000 6800 6900 6800 7000 --
modulus (MPa) Flexural 47 48 49 47 49 48 49 48 49 -- strength (MPa)
Izod impact 2.0 2.1 2.0 1.9 2.2 2.1 2.2 2.0 2.2 -- (kJ/m.sup.2)
[0107] The molded article of Comparative Example A1, which was
obtained by using the recovered styrene-maleic acid copolymer
without the modification, had many bumps and showed a large curing
shrinkage. Therefore, the recovered styrene-maleic acid copolymer
as is was not reusable. On the other hand, the molded articles of
Example A1 to 8, which were obtained by using the modified
styrene-maleic acid copolymers modified with a halogen and/or epoxy
compound, showed no curing shrinkage, and had appearances and
properties comparable to those of the control molded article of the
virgin unsaturated polyester resin that was not a recovered
product. Consequently, it was confirmed that the modified
styrene-maleic acid copolymers were effectively reusable.
Example B
Process for Decomposing Unsaturated Polyester Resin with
Subcritical Water and Process for Separating and Recovering
Styrene-Maleic Acid Copolymer
[0108] An unsaturated polyester resin having a weight-average
molecular weight of 4000 to 5000 was produced by using propylene
glycol as a glycol and maleic anhydride as an organic acid. To a
varnish containing this unsaturated polyester resin was added
styrene in almost equivalent, calcium carbonate as an inorganic
filler was added thereto, and the mixture was cured.
[0109] Next, this cured product (3 g) and an aqueous KOH solution
(15 g) at a concentration of 1.0 mol/l were charged into a reaction
tube, and the internal atmosphere of the reaction tube was replaced
with an argon gas. Then, this reaction tube was tightly-sealed and
immersed in a constant temperature bath at a temperature of
230.degree. C., to thereby decompose the cured product of the
unsaturated polyester resin containing calcium carbonate with
subcritical water for 4 hours. After that, the reaction tube was
cooled, and the contents in the reaction tube were separated by
filtration into an inorganic material and an aqueous solution.
Next, the aqueous solution was adjusted with hydrochloric acid to
an acidic region of pH 4 or less, to thereby form a precipitate of
a water-soluble component, i.e. a styrene-maleic acid copolymer,
contained in the aqueous solution. Then, the styrene-maleic acid
copolymer was separated by filtration and recovered.
Example B1
[0110] The styrene-maleic acid copolymer (5 g) recovered by the
above-mentioned method was dissolved in an alkaline water (95 g)
adjusted to pH 12 with potassium hydroxide. After that,
1,3-dichloro-2-propanol (0.5 g; about 0.40 equivalent relative to
the amount of the carboxylic acid group in the styrene-maleic acid
copolymer) was added thereto, and the mixture was heated with
stirring at 80.degree. C. for 2 hours. Then, the liquid heated with
stirring was uniformly spread into an aluminum vat lined with a
Teflon.RTM. sheet, and allowed to stand for about 30 minutes. Next,
the aluminum vat was heated with a drier at 80.degree. C. for 1
hour, followed by at 100.degree. C. for 2 hours, to thereby obtain
a white film. Then, this film was pulverized to obtain a modified
styrene-maleic acid copolymer as a white powder (modification rate:
10 mol %).
Example B2
[0111] A modified styrene-maleic acid copolymer was obtained as a
white powder (modification rate: 15 mol %) in the same manner as in
Example B1, except that epichlorohydrin (0.5 g; about 0.45
equivalent relative to the amount of the carboxylic acid group in
the styrene-maleic acid copolymer) was added instead of
1,3-dichloro-2-propanol.
Example B3
[0112] A modified styrene-maleic acid copolymer was obtained as a
white powder (modification rate: 17 mol %) in the same manner as in
Example B1, except that 1,4-butanediol diglycidyl ether (0.5 g;
about 0.48 equivalent relative to the amount of the carboxylic acid
group in the styrene-maleic acid copolymer) was added instead of
1,3-dichloro-2-propanol.
Example B4
[0113] A modified styrene-maleic acid copolymer was obtained as a
white powder (modification rate: 35 mol %) in the same manner as in
Example B1, except that 1,3-dichloro-2-propanol (1.5 g; about 1.2
equivalents relative to the carboxylic acid group in the
styrene-maleic acid copolymer) was added.
Comparative Example B1
[0114] A white powder was obtained in the same manner as in Example
B1, except that 1,3-dichloro-2-propanol was not used.
[0115] (Evaluation of Properties)
[0116] The evaluation of the amount of water absorption was carried
out for each of white powders obtained in Examples B1 to B4 and
Comparative Example. The results are shown in Table 2.
TABLE-US-00002 TABLE 2 Ex. Ex. Ex. Ex. Com. B1 B2 B3 B4 Ex. B1
Amount of 55.2 48.9 45.3 1.2 .apprxeq.0 absorption W (g/g)
[0117] Each of the powders of Examples B1 to B3 almost similarly
showed a high water-absorbing property, as represented by an amount
of water absorption of around 50. In contrast, the powder of
Comparative Example was partially dissolved in water, and the
insoluble residue thereof hardly showed a water-absorbing property.
The powder of Example B4 was remained in the form of the white
powder in water, but it showed better water-absorbing property than
the powder of Comparative Example. This is attributed to the fact
that at least 1 or more equivalents of 1,3-dichloro-2-propanol was
used.
[0118] From the results of Examples B1 to B3, it is confirmed that
a styrene-maleic acid copolymer can be modified by the
above-mentioned method into the modified styrene-maleic acid
copolymer according to the present invention, thereby being able to
have a water-absorbing property. In addition, a copolymer (a
styrene-maleic acid copolymer) of a crosslinking moiety and an
organic acid, which is obtained by decomposing a thermosetting
resin comprising a polyester and its crosslinking moiety with
subcritical water at a temperature lower than the thermal
decomposition temperature of the thermosetting resin and recovering
the decomposition product, can be modified by the above-mentioned
method into the modified styrene-maleic acid copolymer according to
the present invention, thereby being reusable as a high
water-absorbing resin. Accordingly, among the components derived
from a thermosetting resin comprising a polyester and its
crosslinking moiety by decomposing the thermosetting resin with
subcritical water at a temperature lower than the thermal
decomposition temperature of the thermosetting resin, glycol and
organic acid monomers are reused as a material for the resin, and a
styrene-maleic acid copolymer is modified and reused as a high
water-absorbing resin. As a result, 80% or more of the components
derived from the resin can be recycled.
* * * * *