Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
2 ~ 0
AGR I CULTURAIJ F I LM
F I ELD OF THE I NVENIT I ON
This invention relat~s to an agricultural film
excellent in heat stability and weather resistance.
_RIOR ART
The agricultural covering films curxently used
for horticultural cultivation houses, tunnels or the like
are mostly polyvinyl chloride films and polyolefin resin
films such as polyethylene films and ethylene-vinyl
acetate copolymer films. These films, commonly known as
agricultural PVC films, agricultural PE films,
agricultural EVA films or the like, are widely used for
such horticultural purposes.
lS The purposes of such greenhouse or t~mnel in
agriculture and horticulture are to artificially adjust or
control the cultivation environment to thereby create an
environme~t suitable for farm products, to enable
cultivation of crops during the period wherein ra:ising
them outdoors is practically impossible or to increase the
producti~ity thereof during the period wherein said
productivity is low. Therefore it is necessary to know
the correlation between various environmental factors
~e.g. light, temperature, humidity, carbon dioxide
concentrati.on, water, soil) and the growing behaviors of
,"
2 0 ~ a
--2--
crops and creating a suitable production environment while
taking the economic features in-to consideration as well.
The performance characteristics required of the
covering materials essenti.al to the formation of
artificial spaces, namely such facilities as greenhouses
and cultivation tunnels, may differ depending on the
purpose of their application and further on the target
vegetable species or the like product species.
Main performance characteristics required of the
covering materials, inclusive of primary covering
materials, heat insulating curtains and the like, for such
houses and tunnels are weather resistance (ability to
endure the sunny outdoor use conditions for a long
period), drippng property (ability to inhibit the
phenomenon of the transparency being decreased due to the
deposit, over the covering film i.nside surface, of minute
water drops resulting from dew condensation because of
high humiAity conditions in the house or tunnel), heat
retention property (ability to maintain high temperature
levels in greenhouses at night) and hiyh light
transmittance (transparency), among others. The term
"dripping" as used in this specif.ication means that water
drops formed by condensatioll on the iilm surace are
caused to flow down withou-t staying on said suriace.
In particula.r, a recent important requirement is
2 0 ~ ..1. 0
that the covering materials have a longer service life for
the reasons that a large number of persons of advanced age
are now engaged in agriculture and that laborsaving is
essential. Thus, a weather resistance improving
technology is earnestly requirQd.
In view of the recent public opinion on the
earth environment problem, more attention is now given on
polyolefin-base covering films which are readily and
completely combustible without any fear of toxic gas
evolution, than on polyvinyl chloride films (agricultural
PVC films) which generate gaseous hydrochloric acid upon
disposal by incineration.
As for the weather resistance improving
technology for polyolefin resins, Japanese Unexamined
Patent Publication (Kokai) No. 86645/1~84, for instance,
discloses a method which comprises using hindered amine
compounds as weather resistance improving agents and,
further, Japanese Unexamined Patent Publication (Kokai)
No. 167350/1990 discloses a method which comprises using a
hindered amine compound, a heat stabilizer and a
hypophosphite compound to thereby attain a high level of
weathe.r resistance.
As for the dripping property improvlng
technolo/~y for polyolefin resin-based covering films,
~apanese Unexamined Patent Publication (Kokai) No.
:
20~a~1~
41240/1987, for instance, discloses a method which
comprises using nonionic surfactants as dripping agents.
As for the heat retention or insulation
improving technology for polyolefin resin-based covering
films, Japanese Examined Patent Publications (Kokoku) No.
5825/1982 and No. 5182/1987, for instance, disclose the
use of various inorganic compounds for heat reten-tion.
In producing these polyolefin resin-based
covering films, heat stabilizers (hindered phenol heat
stabilizers, sulfur-containing heat stabilizers, phosphite
ester heat stabilizers, etc.) are generally added for
providing processing stability and heat stability.
Thus, as a result of successful combination of
the above-mentioned and other kinds of technology, agri-
cultural polyolefin films are now comparable in per-
formance characteristics to agricultural PVC films and are
superior to the latter from the disposability viewpoint.
However, such prior art techniques as mentioned
above are not fully satisfactory, so far as the weather
resistance problem is concerned. This is due to the fact
that agxicultural films are used in particularly sunny
outdoor places, that the portions thereof which are in
contact with the metallic frames of cultivation houses or
tunne:Ls are exposed to considerably high temperature
conditions, and that the film thickness is very small.
~ ~ $ ) ~
Addition of weather resistance improving agents in
increased amounts can of course lead to somewhat more
improvecl weather resistance but, on the other hand, may
disadvantageously cause yellowing of films or bleeding vf
the weather resistance improving agents to thereby impair
the appearance of films. Furthermore, the method
disclosed in Japanese Unexamined Patent Publication
(Kokai) No. 167350~1990, which uses a hindered amine
compound, a heat stabilizer and a hypophosphite compound,
provides agricultural films with excellent heat stability
and weather resistance but still has a problem that, when
the agricultural films are used under high-humidity
conditions, the hypophosphite compound tends to absorb
moisture to thereby cause whitening of the films.
SU~RY OF THE INVENTION
Accordingly, it is an object of the invention to
provide an agricultural film based on an ecologically
advantageous polyolefin resin and having particularly good
heat stability and weather resistance.
We made intensive investigations in an attempt
to improve the weather resistance of agricultuxal films,
in particular polyolefin resin-based agricultural films.
~s a result, we found that an agricul-tural film obtained
by ~orming into a film a composit;.on comprising a
polyolefin resin, a clripping agent, a heat stabilizer, a
2 ~
--5--
weather resistance improving agent and, in addition, a
solution of a hypophosphite compound in an organic solvent
is excellent particularly in heat stability and weather
resistance and, at the same time, resistant -to film
whitening even under high-humidity conditions. The
present invention has been completed based on these
findings.
Thus the invention provides an agricultural film
produced by forming into a film a composition comprising
(a) a polyolefin resin, (b) a dripping agent, ~c) a heat
stabilizer, (d) a weather resistance impro~ing agent, and
(e) a solution of a hypophosphite compound in an organic
solvent.
DETAILED DESCRIPTION OF THE INVENTION
In the following, the present invention is
described in detail.
The polyolefin resin (a) which constitutes the
agricultural film of this invention is one conventionally
used in the art, such as an ~-olefin homopolymer or a
copolymer of an a-olefin as the main component and one or
more comonomers. Useful polyolefin resin includes, among
others, polyethylene, polypropylene, ethylene-a-olefin
copolymers such as ethylene-propylene copolymers,
ethylene-butene-l copolymers, ethylene-4-meth~lpentene-l
copolymers and ethylene-hexene-1 copolymers, ethylene-
7 2 ~
vinyl acetate copolymers, ethylene-acrylic acid
copolymers, ethylene-methyl methacrylate copolymers,
ethylene-vinyl acetate-methyl methacrylate copolymers ~nd
ionomer resins.
S These resins preferably have a melt flow index
of not less than 0.3 g/10 minutes but not more than 4 g/10
minutes, preferably 0.3 g/10 minutes to 2 g/10 minutes.
When the melt flow index is less than 0.3 g/10 minutes,
film processing will become difficult. When said index
exceeds 4 g/10 minutes, the film strength tends to
decrease.
Among the resins mentioned above, low-density
polyethylene or ethylene-~-olefin copolymers having a
density of not more than 0.~35 g/cm , preferably about
0.910 to 0.935 g/cm3, and ethylene-vinyl acetate
copolymers having a vinyl acetate content of not more than
30% by we.ight are preferred because of their excellent
transparency and flexibility and because of
inexpensiveness of the product films.
As the dripping agent (b) in accordance with the
invention, a dripping agent which is conventionally
employed is used to provide the product film with drippiny
property.
As examples of the dripping agent thak can be
usecl in the practice of the invention, nonionic
~$;3~ ~
--8--
surfactants, among others, are preferred.
In selecting the dripping agent, not only the
ability to maintain excellent dripping property but also
such factors as film-forming ability, heat stability,
transparency (or film whitening due to the bleeding of the
dripping agent) and appropriate compatibility with the
polyolefin resin employed should be taken into con-
sideration.
~nong nonionic surfactants, preferred are those
containing, as the hydrophilic moiety~ a polyhydric
alcohol, such as sorbitan, sorbitol, glycerol, diglycerol~
triglycerol, tetraglycerol, polyglycerol, polyethylene
oxide, polypropylene oxide or other polyalkylene oxide,
and, as the hydrophobic moiety, a hydrocarbon chain of 8
to 22 carbon atoms. As typical examples, there may be
mentioned sorbitan fatty acid ester surfactants,
particularly C8-C22 fatty acid esters of sorbitan such as
sorbitan monostearate, sorbitan monopalmitate and sorbitan
monobehenate; glycerol fatty acid ester surfactants,
particularly mono~, di-, tri- or tetra-C8-C22 fatty acid
esters of glycerol, diglycerol or triglycerol such as
glycerol monolaurate, glycerol monopalmitate, glycerol
monostearate, diglycerol dis-tearate and trig:lycerol mono
stearate; polyalkylene glycol fatty acid ester sur-
-factants, particularly those prepared by adding 1 to 10
2 0 ~
moles of C2-C3 alkylene oxide to a C8-C22 fatty acid such
as polyethylene glycol monopalmitate and polyethylene
glycol monostearate; alkylphenol-alkylene oxide adducts,
particularly those prepared by adding 1 to lO moles of C2-
C3 alkylene oxide to a C8-C22 alkyl-substituted phenol
such as polyo~yethylene octylphenyl ether, polyoxyethylene
nonylphenyl ether, and organic acid esters of sorbitan-
glycerol condensates, particularly those wherein the
organic acid moiety is derived from a fatty acid
containing 8 to 22 carbon atoms.
The dripping agent is used in an amount of about
0.5 to 5 parts by weight, preferably about 1.5 to 3 parts
by weight, per lO0 parts by weight of the polyolefin
resin. When amount of the dripping agent is below 0.5
part by weight, the dripping property will not last long.
When said amount exceeds 5 parts by weight, increased
migration of the dripping agent to the film surface tends
to occur, impairing the transparency (causing film
whitening due to the bleeding of the dripping agent) and
allowing increased blocking. In order to op-timize the
total dripping property, i.e., the initial dripping
property, duration of dripping effect, dripping property
in the cold season and dripping property :in the warm
season, it is generally preferable to use two or more
dripping agents in combination.
20~a4~0
--10--
The heat sta~ilizer ~c) to be used in accordance
with the invention includes, among others, hindered phenol
compounds, such as 2,6-dialkylphenol derivatives and 2-
alkylphenol derivatives, sulfur compounds having one or
more (particularly 1 to 4) thiol or thioether bonds each
comprising a bivalen-t sulfur atom, and phosphite ester
compounds containing one or more (particular].y 1 to 3)
trivalent phosphorus atoms.
As examples of the hindered phenol heat
stabilizer, there may be mentioned compounds of the
following formulas (1) to (8).
0
CH3
OH
(2)
CE-I 2CH z COOCI8 f~37
2~ 3
(HO ~,~ CH zCH2 COOCH 2~- C ~3)
HO OII
~CH2 ~ CH2
\ N,C ~/
o z;C~-C~O (~)
C~Iz
OE~
O CH3
HO -~ C 2 H~ COCH2 C--CH ` C J (s
CHI C~I3 2
S C 8 H ~7
HO ~ I`IH ~` ~1 (6)
SC8~17
-12- ~ r~ ~ ~L o
o
OH O--C--CH-CH2
~ C~I2 -~< (7)
CH3 CH3
CH3
HO~ CH CH3
CH3 CH, ( C~I2C~zCE~2 CH~ CH3 (8)
As examples of the sulfur compound heat
stabilizer, there may be mentioned compounds of the
following formulas l 9 ) to ~16).
CH2CH2COOC12H25
F (9)
CH2CH2COOCl2H25
CH2cH2coocl3H27
S (10)
CH2cH2coocl3H27
CH2C~I2~0c)cl4~l29
S (11)
cH2c~l2coocla~H29
2 ~ 8 ~
--13-
CH~CH2cOoclgH37
S ~12)
CH2CH2cOocl8H37
CH2CH2coocl2H25
S (13)
CH2CH2COOCl~H37
~H2scl2scH2cH2coocH2)4c (14)
' O _
j R--SH2CHzC--C ~ Js ( 1S
CH3 2
(R being an alkyl group of 12 to 14 carbon
atoms)
C--SH ( 16)
~I
As examples of the phosphite ester heat
stabilizer, there may be mentioned compounds of the
~ollowing formulas (17) to (33).
P--t--ClQH21)3 (17)
p-~-O-C13H27)3 ~18)
: 25
,
,,
2 ~ . 0
--14--
O--C o H~l ( 19 )
~ / O--Cl3 Hn ( 2 0 )
(~ \P--O CgHI7 (21)
~0/
~) \p~--C~oH21 (22)
~ O
p_O--Cl3H2-~ (23)
~-0
~0 [H~sCs-~O ~ p (24)
~0 ~--p (25)
25 E137C1~3 \ c p--C18E137
oc~ 2 c~ 2
2 0 ~
--15--
19 ~ C~;
-~O-P' `C' \P--O~ (28)
CH3
~- O--P, C, ,P-O~- C~ OH (29)
RO/ C ~- -P~ (30)
(R being an alkyl group of 12 to 15 carbon
atoms
CH3 CH3
~27 C13 ~ '=( ~ ,OCI3~I27
P{) ~ CH -~ O~P, ( 31 )
27 IJ 1 13 27
C3 H7
CH3 CH3
3 Cl O~ ~CH ~'\ O-P ~13
Cfl- ~,~-O-P,
CE3:3
- , :
-16~
~( ~ 0 ~ P - ~ ~ (33)
S The heat stabilizers of the above formulas (1)
through (33) are all known compounds and readily available
on the market.
These heat stabilizers may be used either singly or
in combination.
The heat stabilizer is used generally in an
amount of about 0.01 to 1 part by weight, pre~erably about
0.05 to 0.5 part by weight, per 100 parts by weight of the
polyolefin resin. When the amount is belo~ 0.01 part by
weight, the heat stability improving effect will be poor
while the use thereof in an amount exceeding 1 part by
weight may unfavorably cause bleeding or discoloration of
the heat stabilizer.
As the weather resistance improving agent (d)
according to the invention, there may be mentioned a
hindered amine compound and an ultraviolet absorber, which
are conventionally used.
The hindered amine compound to be used as the
weather resistance improving agent is a 4-substit.uted
2,2,6,6-tetraalkylpiperidirle derivative having a molecular
weight o~ not less than 250, preferably 250 to lO,000.
:
2~5~ ~
-17-
The substituent in position 4 includes for example, a
carboxylic acid residue, an alkoxy group, an alkylamino
group or any of other various groups. The N-position of
the 4-substituted 2, 2, 6, 6-tetraalkylpiperidine
derivative may be substituted by an ~lkyl group,
particularly a Cl~C4 alkyl group, or the like. As typical
examples, there may be mentioned compounds of the
following formulas (34) to (41).
O O
0 ~IN,;}Oc ( CH2 )8--CO~ H (34
O O
~ 11 11
H3C--N~,~ OC - ( CH2 )8--CO ~ N-CH3 (35
O ~ O
H3 C--N~} O-C-C C-O ~ CH3 ( 3 6 )
C4Hg
( R: -CHz -@~ OH
CH2--COO--R
CH -COO--R ~(
I~ M H ~ ( 37 )
CH -COO--
CH2--COO -R
5 ~IO -(~ CHz C~l~ OC~I ! CH? ~ OCCH2 CH~ - ~,r~ OH ( 33 )
~ O ~
-18-
O
{ o-C h-CH~CH2-~-CH2CH2-C ~
ll ll ~ (39)
~H2 CH2 ~- O-C~2 CH2--C -- n
,N~ N-~CH2 ~6 N ~;
NH ~ ~N~ J
o l C8HIJ H H n
_ ~ CH2 )6 ~
lS ~ H H J n
In the formulas (39)-(41), n is an integer of 4
to 7.
The ultraviolet absorber to be used as the
weather resistance improvlng agent in the practice of the
; 20 invention includes ben~ophenone ultraviolet absorbers,
benzotriazole ultraviolet absorbers, benzoate ultraviolet
absorbers and cyanoacrylate ultraviolet absorbers. As
typical examples, there may be mentioned compounds of the
following formulas (42) to (50).
2 0 ~ ~J '~
--19--
~1 0
( 4 2
t C 8 H 17
H 9
¦ ~ N -~ ~ 4 3 )
C H3
H O
¦ ~ N ~, ( 4 4 )
H O t --C 5 H 11
¦ ~N --~ ( 4 5
t C5 11
H 0
H O
C--~OC H 3 ('L 7)
~1 0
~O C X ~ 17
--
2(~5~
-20-
/ ( 4 9 )
~ \ C O O C2 ~I5
~
H O ~ C O ~ (5 0)
The compounds of the above ~ormulas ~34) to (50)
are all known compounds and readilv available on the
market.
The weather resistance improving agent selected
f rom among the foregoing hindered amine compounds and
ultraviolet absorbexs is used generally in an amount of
about 0.01 to 3 parts by weight, preferably a~out 0.05 to
1 part by weight, per 100 parts by weight of the
polyolefin resin. When the amount is less than 0.01 part
by weight, the weather resistance improving effect tends
to be poor while the use thereof in an amount exceed,ing 3
parts by weight may unfavorably result in bleeding of the
ultrav.iolet absorber.
Such weather resistance i.mproviny agents as men
tioned above may be used either singly or in combination.
In the present inven-tion, a solution (e) of a
% ~
-21-
hypophosphite compound in an organic solvent is used.
The hypophosphite compound to be used in accord-
ance with the invention is represented by the general
formula
Xa( 2 2)b (A)
wherein X is a metal ion, ammonium ion or quaternary
phosphonium ion, a and b each is a natural number and a
multiplied by c being equal to b, wherein c is the valence
of X.
Typical examples of the hypophosphite compound
are lithium hypophosphite, sodium hypophosphite, potassium
hypophosphite, magnesium hypophosphite, calci~n hypo-
phosphite, zinc hypophosphite, titanium hypophosphite,
vanadium hypophosphite, molybdenum hypophosphite,
manganese hypophosphite, cobalt hypophosphite, ammonium
hypophosphite, butylammonium hypophosphite, diethyl-
ammonium hypophosphite, triethylammonium hypophosphite,
tetraethylammonium hypophosphite, tetrabutylphosphonium
hypophosphite and tetraphenylphosphonium hypophosphite.
The hypophosphite compounds specifically mentioned above
are known compounds or can readily be synthesized from
commercially available corresponcling salts by a
conventional method.
Such hypophosphite compounds as specifically
mentioned above may be used either singly or in
2 ~3 ~
-22-
combination.
The organic solvent to be used for dissolving
the hypophosphite compound is preferably an organic
solvent which can dissolve the hypophosphite compound and
which has a boiling point of not lower than the resin
processiny temperature for film forming. As typical
examples, there may be mentioned protic polar solvents,
such as polyhydric alcohols and polyamines, and aprotic
polar solvents, such as alkyl sulfoxides. Preferred
protic polar solvents ~re ethylene glycol, diethylene
glycol, polyethylene glycol (molecular weight: about 150
to 50,000), propylene glycol, polypropylene glycol
(molecular weight~ about 134 to 50,000), glycerol,
diglycerol, hexaglycerol, trimethylolpropane,
hexamethylenediamine and the like. Dimethyl sulfoxide and
the like are preferred aprotic polar solvents. These may
be used either alone or in combination.
The hypophosphite compound is used generally in
an amount of about 0.01 to 2 parts by weight per 100 parts
by weight of the polyolefin resin. If the amount is less
than 0.01 part by weight, the heat stability and weather
resistance improving e~fects may not be sufficient:Ly
improved. If the amount exceeds 2 parts by weight, the
transparency may occasionally be impaired.
The amount of the organic solvent for dissolving
~ ~ (?, .~
-23-
the hypophosphite compound is preferably such that a
solution containing the hypophosphite compound in said
organic solvent at a concentration not higher than the
saturation concentration is used in an amount of about
0.01. to 5 parts by weight per 100 pa:rts by weight of the
polyolefin resin. The hypophosphite compound
concentration in the solution containing the hypophosphite
compound is preferably about 0.1% to about 80%, more
preferably about 1% to about 50% by weight, but in any
event is not higher than the saturation concent.ration.
At any rate, it is important that the hypophosphite
compound is used as dissolved in said organic solvent,
namely in the form of a solution containing the
hypophosphite compound in said organic solvent at a
concentration not higher than the saturation
concentration, and that the amount of the hypophosphite
compound is about 0.01 to 2 parts by weight per 100 parts
by weight of the polyolefin resin.
For improving the heat retention at night in
cultivation houses or tunnels, t'he agricultural film of
this invention may ~'urther contain an inorgan.ic compound
for heat retention, if so desired. Said inorganic
compound includes, among others, oxides, hydro~ides,
carbonates, sulfates, phosp'hates, silicates, aluminates r
aluminosilicates and the like of such metals as lithium,
' .
-24- 2~
sodium, potassium, magnesium, calcium, zinc, aluminum,
silicon and titanium. ~hese may be used either alone or
in combination.
~nong such inorganic compounds~ maynesium oxide,
calcium oxide, aluminum oxide, silicon oxide, titanium
oxide and the like may be mentioned as the oxides; lithium
hydroxide, magnesium hydroxide, calcium hydroxide,
aluminum hydroxide and the like as the hydroxides;
magnesium carbonate, calcium carbonate and the like as the
carbonates; potassium sulfate, magnesium sulfate, calcium
sulfate, zinc sulfate, aluminum sulfate and the like as
the sulfates; lithium phosphate, sodium phosphate,
potassium phosphate, calcium phosphate and the like as the
phosphates; magnesium silicate, calcium silicate, aluminum
silicate, titanium silicate and the like as the silicates;
sodium aluminate, potassium aluminate, calcium aluminate
and the like as the aluminates; and sodium
aluminosilicate, potassium aluminosilicate, calcium
aluminosilicate and the like as the aluminosilicates.
Mention may further be made of basic double salts,
t~pically hydrotalcite, as double salts composed of those
inorganic compounds mentioned above.
Among the inorganlc compounds specifically mell-
tioned above, silicon oxide, calcium phosphate, aluminum
2S silicate, hydrotalci.te and the like are preferred since,
-25-
when incorporated in synthetic resins, they provide the
resins with good heat-retaining property without impairing
thQ transparency thereof.
The inorganic compound is used in the form of a
powder. The smaller the particle size of the powder is,
the more uniform the dispersion attainable is. From the
strength and transparency viewpoints, an average particle
size of about 0.5 to 10 ~m is preferred.
When such an inorganic compound is used, said
inorganic compound is used in an amount of not more than
20 parts by weight, preferably abo~t 0.5 to 20 parts by
weight, more preferably about 1 to 15 parts by weight, per
100 parts by ~eight of the polyolefin resin. If the
amount is below 0.5 part hy weight, the heat retention
improving effect will not be sufficient. Conversely, the
use thereof in an amount exceeding 20 parts by weight
tends to impair the film strength and/or transparency.
If desired, the agricultural film of this
invention may further contain a conventional anti:Eogging
agent, lubricant, pigment and like additives.
The agricultural film of the invention is
produced in ,the following manner. The polyolefin resi.n is
admixed and kneaded w:ith a dripping agent, a solution of
hypophosphite compound in an organic solvent, a heat
stabilizer and a weather resistance improving agent,
2 0 ~ 3 ~ 3 0
-26-
optionally together with ~arious other additives, such as
the inorganic compound mentioned above, each in an
appropriate amount, in a conventional mixing and/or
kneading device such as a ribbon blender, supermixer,
Banbury mixer or single-screw or twin~screw extruder. The
subsequent film production can be conducted in the
conventional manner, for example by using the calendering
T die extrusion, or inflation technique. It is also
possible to produce a two-layer film composed of two
different compositions or a three-layer film composed of
two or three different compositions using the T die
extrusion or inflation technique. A three-layer film,
wherein its middle layer is composed of a resin
compositi.on containing an inorganic compound, will
advantageously have a much improved level of transparency.
The agricultural film of the invention generally
has a thickness of about 0.02 to 0.3 mm, preferably about
0.03 to 0.2 mm. When the film thickness is less than 0.02
mm, the film strength will tend to be insufficient.
Conversely, a thickness exceeding 0.3 mm is less desirable
since such works as film seaming and application as
covering material often become difficult to perform.
The a~ricultural film provided by the present
invention is almost free from whitening due to absorption
of moisture, even when used under high humidity conditions
-27~ '3~ ~ ~
in the field of agriculture as a covering of a cultivation
house or t-mne1.. Said film shows very good heat stability
in the production process and very good weather resistance
when used as a covering film. Thus it can be used as a
material useful in horticulture.
The following examples illustrate the invention
in further detail. However, they are by no means
limitative of the scope of the invention. The test
methods used in the e~amples are as follows.
Water immersion test
Square test specimens (10 cm x 10 cm) cut from
each film sample were immersed in water at 23C for 24
hours and the extent of film whitening was evaluated
according to the following criteria:
A : Little whitening
C : Whitening
Heat stability test
Test specimens (3 cm x 3 cm, 1 mm in thickness)
were allowed to stand in air at 190C and the change in
color was evaluated according to the following criteria:
A : Little discoloration
B : Slight yellowing
C Yellowing or brown.ing
Weatherin test
Dumbbell-shaped test specimens (prepared by
~.
2 ~ 0
-2~-
punching with a JIS No. 1 dumbbell die) were allowed to
age in Eye Super W Tester (trademark; manufactured by Eye
Graphics Co., Ltd.; model S W -W11 modified) under the
following conditi.ons: luminous energy 100 mW/cm2, distance
from light source 24 cm, -temperature of blowing air 60C,
relative h~midity 33%.
Th2 aged test specimens were subjected to
tensil.e test using Autograph DSS100 (trademark;
manufactured by Shimadzu Corp.) for determining elongation
(%) and the weathering test period after which ~he
elongation was half the initial value (hereinafte:r
referred to as "weathering half-life") was determined for
each sample. The longer this half-life is, the better the
. weather resistance i5.
Example 1
To 100 parts by wei.ght of an ethylene-vinyl
acetate copoplyrner (trademark: Evatate D2011, vinyl
acetate content 5~ by weight; melt flow index (MI) = 2.0
g/10 minutes; manufactured by Sumitomo Chemical Company,
Limited), which was employed as a polyolefin resin, were
added 1.4 parts by weight of monoglycerol monostearate and
0.6 part by weight of diglycerol distearate (each as a
dripping ager-t), 4 parts by weight of alumirlum silicate
ttrademark: Silton AMT; manufactured by Mizusawa
Industrial Chemlcals Ltd.) (inorganic compound for heat
~ 3t~
-29-
retention), 0.1 part by weight of 2,6-di tert-butyl-
hydroxytoluene of the foregoing formula (1) (as a heat
stabllizer), 0.4 part by weight of the hindered amine
compound of the foregoing formula (40) (HALS 944;
trademark: Chimassorb 944-LD; manufactured by Ciba-Geigy)
(as a weather resistance improving agent), 0.15 part by
weight of a sodium hypophosphite solution (20% by weight
sodium hypophosphite, 80% by weight diethylene glycol) and
0.2 part of stearamide (as a lubricant).
The resulting mixture was kneaded in a Banbury
mixer at 150C for 5 minutes and then granulated using a
pelletizer. The -thus-obtained composition pellets wer~
fo~ned into a film at 180C on an inflation film-forming
machine to give a film having a thickness of 75 ~m. This
film was subjected to weathering test and water imrnersion
test.
Separately, the same pellets as mentioned above
were formed into a 1-rNn-thick sheet at 180C using a press
molding machine and this sheet was subjected to heat
stability test.
As shown in Table 1, good results were obtained.
~L~.le 2
A film and a sheet were produced in the same
manner as in Example 1 except that low-density poly-
eth~lene (tradernark: Sumi.kathene F208-0; manufactured by
20 ~:3/11~.
-30-
Sumitomo Chemical Company, Limited; MI = l.5 g/lO minutes)
was used as the polyolefin resin.
The same tests as performed in Example l were
performed with the film and sheet obtained. As shown in
Table l, good results were obtained.
Example 3
A film and a sheet were produced in the same
manner as in Example l except that the hindered amine
compound ~f the foregoing foxmula (39) (HALS 622;
trademark: Tinuvin 622-LD; manufactured by Ciba-Geigy~ was
used as the weather resistance improving agent.
The same tests as performed in Example l were
performed with the film and sheet obtained. As shown in
Table l, good results were obtained.
Exam~le 4
A film was produced in the same manner as in
Example l except that l par-t by weight of the ultraviolet
absorber of the foregoing formula (42) ( W A 130;
trademark: Sumisorb 130; manufactured by Sumitomo Chemical
Company, Limited) was used as the weather resistance
improving agent.
The film obtained was subjected to water
immersion test. ~6 shown in Table l, a good result was
obtained.
ComParative Example_l
2 ~'3/~
-31-
A film and a sheet were produced in the same
manner as in Example 1 except that the use of the sodium
hypophosphite solution was omitted.
The same tests as performe<1 in Example 1 were
performed with the film and sheet obtained. As shown in
Table 2, they were inferior in weather resistance and heat
stability.
Comparative ExamPle 2
A film and a sheet were produced in the same
; 10 manner as in Example 1 except tha-t 0.03 part by weight of
sodium hypophosphite powder was used in lieu of the sodium
hypophosphite solution.
The same tests as performed in Example 1 were
performed with the film and sheet obtained. As shown in
- 15 Table 2, the film showed whitening in the water immersion
test, revealing that it was inferior from the performance
characteristics viewpoint.
Comparative Example 3
A film and a sheet were produced in the same
manner as in Example 2 except that the use of the sodium
hypophosphi.te solution was omitted.
The same tests as performed in Example 1 were
perfor~ned with the film and sheet obtained. As shown in
Table 2, they were inferior in weather resistance and heat
stabili.ty.
2 ~
-32-
Com~arative Exam~le 4
A film and a sheet were produced in the same
manner as in Example 2 except that 0.03 part by weight of
sodium hypophosphi.te powder was used in lieu of the sodium
hypophosphite solution.
The same tests as performed in Example 1 were
performed with the film and sheet obtained. As shown in
Table 2, the film showed whitening in the water immersion
test, revealing that it was inferior from the performance
characteristics viewpoint.
ComPar~tive Example 5
A film and a sheet were produced in the same
manner as in Example 3 except that the use of the sodium
hypophosphite solution was omittedO
The same tests as perfoxmed in Example 1 were
performed with the film and sheet obtained. As shown in
Table 2, they were inferior in weather resistance and heat
stability.
Compaxative Example 6
A film was produced in the same manner as in
Example 4 except that 0.03 part by weight of sodium
hypophosphite powder was used in lieu of the sodium
hypophosphite solution.
The sheet was subjected to water immersion test.
As shown ln ~able 2/ the :~ilm showed whitening in the
2~`Q ~{~
-33-
water immersion test, revealing that it was inferior from
the performance characteristics viewpoint.
In Tables 1 and 2, EVA stands for e-thylene-vinyl
acetate copolymer, and LDP~ stands for low-density
polyethylene.
2 0 ~ 0
--34--
Table 1
_Composition Performance characteristics
Resin Weather Hypophos- Water ~leat Weathering
resistance phite immersion stability test
improving compound test test (weathering
agent solution (8 hours) half-life)
(parts by (parts by (hours~
weight) weight)
Example 1 EVA HALS944 Sodium A A lS0
(0.4) hypophos-
15 phite
solution
(O.15)
Example 2 LDPE HALS944 Sodium A A 150
20(0.4) hypophos-
phite
solution
: (0.15)
Example 3 EVA HALS622Sodium A A 130
~0.4) hypophos-
phite
solution
(0.15)
-
Example 4 EVA WA130 Sodium A --- ---
(1.0) hypophos-
phite
solution
( _15)
2 ~ 8
-35-
Table 2
Composition Performance characteristics
5 ~
Resin Weather Hypophos- Water Heat Weathering
resistance phite immersion stability test
improving compound test test (weathering
agent solution (S hours) half-life)
(parts by (parts by (hours)
weight) weight) _ _
Compara- EVA HALS944 None A C 70
tive (0.4)
Example 1
Compara- EVA HALS944 Sodium C B 130
tive (0.4) hypophos-
Example 2 phite
powder
(0.03) _ - -
Compara- LDPE HALS944 None A C 80
tive (0.4)
Example 3
Compara- LDPE HALS944 Sodium C B 130
tive (0.4) hypophos-
Example 4 phite
powder
(0.03)
Compara- EVA HALS62Z Nane A C 60
tive (0.4)
Example 5
Compara- EVA W A130 Sodium C --- ---
tive (1.0) hypophos-
Example 6 phite
powder
. (0.03)
