JP2023075245A - Degradation inhibitor, resin composition and molding - Google Patents

Abstract

To provide a degradation inhibitor that sufficiently exhibits the effect of addition of cellulose, gives excellent mechanical strength to a molding, and is effective in inhibiting degradation due to metal ions, and a resin composition and a molding containing the degradation inhibitor.SOLUTION: A degradation inhibitor can inhibit degradation of polyolefin due to metal ions. The degradation inhibitor has a first structural unit based on alkyl (meth) acrylate, and a second structural unit based on an acryl monomer having an amide group, with a weight average molecular weight of 5,000-100,000.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a deterioration inhibitor, a resin composition and a molded product.

Polyolefin is widely used as a constituent material for automobile parts and electronic parts because it is lightweight and has excellent moldability and mechanical strength.
However, when polyolefin is in contact with copper for a long period of time, deterioration called so-called copper damage is likely to occur. Degradation of polyolefin due to contact with metal may also occur with metals other than copper.
In order to overcome such drawbacks, a copper damage inhibitor is added to polyolefin (see, for example, Patent Document 1).

On the other hand, cellulose nanofibers, which have been developed in recent years, are natural raw material nanofillers derived from vegetable oils, and are attracting attention as composite materials for resins with low specific gravity and high strength. Moreover, by adding cellulose nanofibers to polyolefin such as polyethylene, a resin composition capable of imparting excellent mechanical strength to molded articles is known (see, for example, Patent Document 2).
However, these resin compositions cannot prevent metal deterioration such as copper damage, and if metal deterioration occurs, there is a problem that the effect of improving the mechanical strength obtained by the addition of cellulose cannot be sufficiently obtained. there were.

Therefore, when reinforcing polyolefin with cellulose, there has been a demand for a material that can fully exhibit the effect of adding cellulose and prevent metal deterioration such as copper damage.

JP 2014-107176 A Patent Publication No. 6197941

The present invention provides a deterioration inhibitor that sufficiently exerts the effect of adding cellulose, imparts excellent mechanical strength to a molded product, and is excellent in the effect of inhibiting deterioration due to metal ions, and a resin composition containing such a deterioration inhibitor. It is to provide products and molded products.

Such objects are achieved by the present invention of the following (1) to (10).
(1) A deterioration inhibitor capable of suppressing deterioration of polyolefin due to metal ions,
(Meth) comprising a first structural unit based on an acrylic acid alkyl ester and a second structural unit based on an acrylic monomer having an amide group,
A deterioration inhibitor characterized by having a weight average molecular weight of 5,000 to 100,000.
(2) The deterioration inhibitor according to (1) above, wherein the alkyl group of the first structural unit has 6 to 18 carbon atoms.

(3) The deterioration inhibitor according to (1) or (2) above, wherein the first structural unit accounts for 25 to 50% by mass of all structural units constituting the deterioration inhibitor.
(4) The deterioration inhibitor according to any one of (1) to (3) above, wherein the second structural unit accounts for 50 to 75% by mass of all structural units constituting the deterioration inhibitor. .
(5) The deterioration inhibitor according to any one of (1) to (4) above, wherein the metal ion is at least one of copper ion, manganese ion and cobalt ion.

(6) the deterioration inhibitor according to any one of (1) to (5) above;
A resin composition comprising a polyolefin.
(7) The resin composition according to (6) above, wherein the amount of the deterioration inhibitor contained in the resin composition is 1% by mass or more.
(8) The resin composition according to (6) or (7) above, which further contains cellulose fibers.
(9) A molded article comprising a molded article of the resin composition according to any one of (6) to (8) above.
(10) The molded article according to (9) above, which is an automobile part.

Since the deterioration inhibitor of the present invention is an acrylic polymer having an amide group, it has excellent ability to trap metal ions and has high compatibility with polyolefin. Such acrylic polymers can also be produced relatively inexpensively.
Furthermore, in the deterioration inhibitor of the present invention, the amide group has high affinity with cellulose fibers, and the alkyl group and main chain have high affinity with polyolefin. Therefore, the deterioration suppressing agent is excellent in defibrating properties of cellulose fibers and can uniformly mix cellulose fibers and polyolefin. Therefore, according to the present invention, the effect of addition of cellulose fibers is fully exhibited, and a molded product having excellent mechanical strength can be obtained.

BEST MODE FOR CARRYING OUT THE INVENTION The deterioration inhibitor, resin composition and molded article of the present invention will be described in detail below based on preferred embodiments.
As a result of intensive studies to solve the above problems, the present inventors have found that a first structural unit based on a (meth)acrylic acid alkyl ester and a second structural unit based on an acrylic monomer having an amide group. and having a weight-average molecular weight of 5,000 to 100,000, a deterioration inhibitor having high compatibility with polyolefin and excellent ability to trap metal ions can be obtained, thereby completing the present invention. reached.

In general, many deterioration inhibitors (for example, copper damage inhibitors) are low-molecular-weight compounds having a molecular weight of 1,000 or less. On the other hand, the deterioration inhibitor of the present invention is an acrylic polymer having a polyolefin structure in its main chain and alkyl groups in its side chains, so it is highly compatible with polyolefin.
In addition, since the deterioration inhibitor of the present invention has an amide group, for example, by coordinating with metal ions, it effectively captures metal ions, suppressing or inactivating polyolefin deterioration due to metal ions. become In particular, by increasing the number of amide groups in the deterioration inhibitor, the ability to trap metal ions can be further enhanced.

The number of carbon atoms in the alkyl group of the first structural unit is not particularly limited, but is preferably 6-18, more preferably 8-15. A deterioration inhibitor having an alkyl group with such a number of carbon atoms further increases compatibility with polyolefin.
Further, the amount of the first structural unit in all structural units constituting the deterioration inhibitor is preferably about 25 to 50% by mass, more preferably about 30 to 45% by mass. As a result, the number (concentration) of alkyl groups in the deterioration inhibitor becomes appropriate, and the compatibility between the deterioration inhibitor and the polyolefin is further improved.

On the other hand, the amount of the second structural unit in all structural units constituting the deterioration inhibitor is preferably about 50 to 75% by mass, more preferably about 55 to 70% by mass. As a result, the number (concentration) of amide groups in the deterioration inhibitor becomes appropriate.
Specifically, the concentration of the amide group in the deterioration inhibitor is preferably about 1.4 to 9.9 mmol/g, more preferably about 2.8 to 9.2 mmol/g. The concentration of the amide group is a value calculated from the charged amount of the monomer, which is the raw material of the deterioration inhibitor. By containing an amide group at such a concentration, the ability of the deterioration inhibitor to trap metal ions is further improved.

The weight average molecular weight of the deterioration inhibitor may be from 5,000 to 100,000, preferably from about 10,000 to 50,000. Such a weight-average molecular weight deterioration inhibitor further increases compatibility with polyolefin.
Here, the weight average molecular weight is a value determined by polystyrene conversion based on gel permeation chromatography (hereinafter referred to as "GPC") measurement.

The amount of each structural unit contained in the deterioration inhibitor is substantially equal to the amount of each monomer contained in the monomer component that is the raw material of the deterioration inhibitor.
The deterioration inhibitor of the present invention is obtained by polymerizing a (meth)acrylic acid alkyl ester and an acrylic monomer having an amide group. Therefore, such a deterioration inhibitor can be synthesized (manufactured) at a relatively low cost.

In this specification, the notation of "(meth)acrylic acid" represents either one or both of "acrylic acid" and "methacrylic acid". The notation of "(meth)acrylate" represents either one or both of "acrylate" and "methacrylate". The notation of "(meth)acrylamide" represents either one or both of "acrylamide" and "methacrylamide". Alkyl groups also include cycloalkyl groups.

(Meth)acrylic acid alkyl esters include, for example, cyclohexyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate and the like. (Meth)acrylates are preferred. By using lauryl (meth)acrylate, the compatibility of the deterioration inhibitor with polyolefin can be particularly enhanced. In addition, (meth)acrylic-acid alkylester may be used individually by 1 type, or may use 2 or more types together.

Examples of acrylic monomers having an amide group include (meth)acrylamide, N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-propyl(meth)acrylamide, N,N-dimethyl(meth) acrylamide, N,N-diethyl (meth)acrylamide, N,N-dipropyl (meth)acrylamide, N-isopropyl (meth)acrylamide, N-dodecylacrylamide, N-propoxymethylacrylamide, 6-(meth)acrylamidohexanoic acid, (Meth)acryloylmorpholine, N-methylol (meth)acrylamide, N-(2-hydroxyethyl) (meth)acrylamide, N,N-dimethylaminopropyl (meth)acrylamide, N-[2,2-dimethyl-3- (dimethylamino)propyl]acrylamide and the like. In addition, an acrylic monomer may be used individually by 1 type, or may use 2 or more types together.

In addition to the (meth)acrylic acid alkyl ester and the acrylic monomer having an amide group, other monomers can be used as necessary for the synthesis of the deterioration inhibitor.
Other monomers include, for example, (meth)acrylic acid, (anhydride) maleic acid, fumaric acid, (anhydride) monomers having a carboxyl group such as itaconic acid; 2-methylaminoethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, γ-methacryloxypropyl trimester (Meth)acrylates having functional groups such as toxyxylane, vinyltriethoxysilane, glycidyl (meth)acrylate; methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, isobornyl ( meth)acrylate, benzyl (meth)acrylate, diethylene glycol di(meth)acrylate, di(meth)acrylate-1,4-butanediol, di(meth)acrylate-1,6-hexanediol, tri(meth)acryl acid trimethylolpropane, glyceryl di(meth)acrylate, styrene, α-methylstyrene, paramethylstyrene, chloromethylstyrene and the like. In addition, another monomer may be used individually by 1 type, or may use 2 or more types together.

The deterioration inhibitor is, for example, a (meth)acrylic acid alkyl ester, an acrylic monomer, and optionally other monomers in an organic solvent in the presence of a polymerization initiator at 60 to 140 ° C. It can be produced by radical polymerization at temperature. In addition, the organic solvent may be removed by a solvent removal step after the radical polymerization.

Examples of organic solvents include aromatic solvents such as toluene and xylene; alicyclic solvents such as cyclohexanone; ester solvents such as butyl acetate and ethyl acetate; isobutanol, normal butanol, isopropyl alcohol, sorbitol, Cellosolve solvents such as propylene glycol monomethyl ether acetate; ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone; and the like can be used. In addition, a solvent may be used individually by 1 type, or may use 2 or more types together.

Examples of polymerization initiators include 2,2′-azobis(isobutyronitrile), 2,2′-azobis(2-methylbutyronitrile), azo compounds such as azobiscyanovaleric acid; tert-butylperoxy pivalate, tert-butyl peroxybenzoate, tert-butyl peroxy-2-ethylhexanoate, di-tert-butyl peroxide, di-tert-butyl hydroperoxide, cumene hydroperoxide, benzoyl peroxide, tert - organic peroxides such as butyl hydroperoxide; and inorganic peroxides such as hydrogen peroxide, ammonium persulfate, potassium persulfate and sodium persulfate. In addition, a polymer initiator may be used individually by 1 type, or may use 2 or more types together.
Moreover, it is preferable to use such a polymerization initiator in an amount of about 0.1 to 10% by mass with respect to the total amount of monomers that are raw materials of the deterioration inhibitor.

The deterioration suppressing agent as described above can suppress the deterioration of polyolefin caused by metal ions. Various kinds of metal ions exist, but at least one of copper ions, manganese ions and cobalt ions is preferable. These metal ions have a pronounced degrading effect on polyolefins. Therefore, it is effective to trap these metal ions, and the deterioration inhibitor of the present invention has a particularly high ability to trap them.

The resin composition of the present invention contains the deterioration inhibitor and polyolefin. As described above, the deterioration suppressing agent is excellent in ability to capture metal ions. Therefore, even if the resin composition is in contact with a metal such as copper for a long period of time and the metal ions diffuse into the resin composition, the deterioration inhibitor efficiently captures the metal ions. As a result, the metal ions are rendered harmless (inactivated), and deterioration of the polyolefin is suppressed or prevented. Therefore, the deterioration inhibitor can also be called a metal deactivator.

Examples of polyolefin include polyethylene, polypropylene, and polybutylene. Polypropylene is preferable because it is particularly susceptible to metal ions.
The amount of the deterioration inhibitor contained in the resin composition is preferably 1% by mass or more, more preferably about 2 to 3% by mass.

The molded article of the present invention includes molded articles obtained by molding the resin composition. Such molded articles are excellent in weather resistance because deterioration of the polyolefin is suppressed by the deterioration inhibitor.
Furthermore, the resin composition preferably contains cellulose fibers. When the resin composition contains cellulose fibers, the mechanical strength of the molded article (molded article) can be improved.

In the deterioration inhibitor of the present invention, the amide group has high affinity with cellulose fibers, and the alkyl group and main chain have high affinity with polyolefin. Therefore, the deterioration suppressing agent is excellent in defibrating properties of cellulose fibers and can uniformly mix cellulose fibers and polyolefin.
As a method for defibrating cellulose fibers, a resin composition containing cellulose fibers is subjected to extruders such as a bead mill, an ultrasonic homogenizer, a single-screw extruder and a twin-screw extruder, a Banbury mixer, a grinder, a pressure kneader, A method of kneading using a kneader such as a two-roll kneader may be used.

Cellulose fibers (pulp) may be wood pulp or non-wood pulp. Wood pulp includes mechanical pulp and chemical pulp, and among these, chemical pulp having a low lignin content is preferred. Chemical pulp includes, for example, sulfide pulp, kraft pulp, alkali pulp and the like. On the other hand, non-wood pulps include, for example, pulps made from straw, bagasse, kenaf, bamboo, reeds, kozo, flax, and the like.

The resin composition, if necessary, polyethylene-based resin (PE) (high-density polyethylene (HDPE), low-density polyethylene (LDPE), bio-polyethylene), vinyl chloride resin, styrene resin, (meth)acrylic resin, vinyl ether resin Nylon resins; Polyamide resins; Polycarbonate resins; Polysulfone resins; Polyester resins; Thermoplastic resins such as cellulose resins such as triacetylated cellulose and diacetylated cellulose; Surfactants, starches, polysaccharides such as alginic acid, natural proteins such as gelatin, glue and casein, tannins, zeolites, ceramics, inorganic compounds such as metal powders, coloring agents, plasticizers, fragrances, pigments, flow control agents, Additives such as a leveling agent, a conductive agent, an antistatic agent, an ultraviolet absorber, an ultraviolet dispersant, and a deodorant may be contained.

INDUSTRIAL APPLICABILITY The resin composition of the present invention can be used for the production of various molded articles because molded articles having excellent mechanical strength can be obtained. In particular, since the deterioration suppressing agent exerts the effect of suppressing deterioration due to metal ions, the molded product is preferably a metal part or an automobile part, which is often exposed to contact with metal powder or the like.
Although the deterioration inhibitor, the resin composition, and the molded product of the present invention have been described above, the present invention is not limited to the configurations of the above-described embodiments.
For example, the deterioration inhibitor, resin composition and molded article of the present invention may additionally have any other configuration in the configuration of the above-described embodiment, or may have any other configuration that exhibits the same function. configuration may be substituted.

EXAMPLES The present invention will now be described more specifically with reference to examples and comparative examples.
1. Production of deterioration inhibitor [deterioration inhibitor 1]
First, 123 parts by mass of isopropyl alcohol (hereinafter referred to as "IPA") was added to a four-necked flask equipped with a stirrer, reflux condenser, thermometer and nitrogen blowing tube, and the temperature was raised to 80°C.
Next, to this IPA, 135.3 parts by mass of acrylamide, 108.2 parts by mass of lauryl methacrylate, 2.5 parts by mass of methyl acrylate, 246 parts by mass of IPA, 4 parts by mass of a polymerization initiator (Wako Pure Chemical Co., Ltd. "V-59", azo initiator), and 10 parts by mass of methyl ethyl ketone (hereinafter referred to as "MEK".) Was added dropwise over 2 hours to react at 73 to 77 ° C. did
After that, the inside of the reaction vessel was held in the same temperature range for 2 hours to complete the polymerization reaction.
After removing the solvent (0.08 to 0.095 MPa, 60 ° C.) from the obtained resin solution using a vacuum pump, it is dried by heating at 80 ° C. for 30 minutes using a dryer, and deterioration inhibitor 1 is obtained as a solid. got

[Degradation inhibitor 2]
First, in the same manner as described above, 123 parts by mass of isopropyl alcohol (hereinafter referred to as "IPA") was charged into a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen blowing tube, and the temperature was raised to 80°C. heated up.
Then, to this IPA, 110.7 parts by weight acrylamide, 110.7 parts by weight lauryl methacrylate, 12.3 parts by weight methyl acrylate, 12.3 parts by weight 2-hydroxyethyl methacrylate, 246 parts by weight IPA , 4 parts by mass of a polymerization initiator (“V-59” manufactured by Wako Pure Chemical Industries, Ltd., an azo initiator), and 10 parts by mass of methyl ethyl ketone (hereinafter referred to as “MEK”). It was added dropwise over time and the reaction was carried out at 73-77°C.
After that, the inside of the reaction vessel was held in the same temperature range for 2 hours to complete the polymerization reaction.
After removing the solvent (0.08 to 0.095 MPa, 60 ° C.) from the obtained resin solution using a decompression pump, it is dried by heating at 80 ° C. for 30 minutes using a dryer, and deterioration inhibitor 2 is obtained as a solid. got

2. Measurement of Weight Average Molecular Weight of Deterioration Inhibitor The weight average molecular weight of the deterioration inhibitor was measured under the following GPC measurement conditions.
[GPC measurement conditions]
Measuring device: High-speed GPC device (“HLC-8220GPC” manufactured by Tosoh Corporation)
Column: The following columns manufactured by Tosoh Corporation were connected in series and used.
"TSKgel G5000" (7.8mm I.D. x 30cm) x 1 "TSKgel G4000" (7.8mm I.D. x 30cm) x 1 "TSKgel G3000" (7.8mm I.D. x 30cm) x 1 Book "TSKgel G2000" (7.8 mm ID x 30 cm) x 1 Detector: RI (differential refractometer)
Column temperature: 40°C
Eluent: Tetrahydrofuran (THF)
Flow rate: 1.0 mL/min Injection volume: 100 μL (tetrahydrofuran solution with a sample concentration of 4 mg/mL)
Standard sample: A calibration curve was created using the following monodisperse polystyrene.

(monodispersed polystyrene)
"TSKgel standard polystyrene A-500" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-1000" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-2500" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-5000" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-1" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-2" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-4" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-10" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-20" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-40" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-80" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-128" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-288" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-550" manufactured by Tosoh Corporation

The weight average molecular weight of deterioration inhibitor 1 obtained above was 15,000, and the weight average molecular weight of deterioration inhibitor 2 was 17,000.

3. Confirmation of deterioration suppression effect by metal ions 3-1. Production of pellets (Examples 1-6)
A deterioration inhibitor and polypropylene ("PP J106G" manufactured by Prime Polymer Co., Ltd.) are mixed in a Henschel mixer for 2 minutes at the ratio shown in Table 1 below, and heated to 180 to 230 ° C. A twin-screw extruder (Co., Ltd. (manufactured by Technobell) to obtain pellets.

(Comparative example 1)
Pellets were obtained in the same manner as in the above example, except that 3 parts by mass of copper damage inhibitor 1 (manufactured by ADEKA, "CDA-6") represented by the following formula and 97 parts by mass of polypropylene were mixed. Obtained. Incidentally, the molecular weight of the copper damage inhibitor 1 is 468.

(Comparative example 2)
Pellets were obtained in the same manner as in the above example, except that 3 parts by mass of copper damage inhibitor 2 (manufactured by BASF Japan, "MD1024") and 97 parts by mass of polypropylene were mixed. In addition, the molecular weight of the copper damage inhibitor 2 is 552.

(Comparative Example 3)
Pellets were obtained in the same manner as in the above examples, except that the deterioration inhibitor and the copper damage inhibitor were omitted.

3-2. Evaluation of deterioration suppression effect First, the obtained pellet is molded with an injection molding machine (manufactured by Sumitomo Heavy Industries, "iM18") at a melting point of 180 to 230 ° C. and a mold of 50 ° C., ASTM No. 4 (1.6 mm thickness). A sample piece was produced.
Next, each sample piece was placed on a flat plate made of tetrafluoroethylene (Sample A) and sandwiched between copper plates (Sample B) and left in an oven at 140° C. for one day.

After one day, the L value of each sample A and B was measured by a reflection method according to the method of JIS Z 8722:2009 using a spectrophotometer ("CM-5 type" manufactured by KONICA MINOLTA).
Based on the measured values, the rate of decrease in L value from sample A to sample B was determined.
The above results are shown in Table 1 below.

As shown in Table 1, Examples 1 to 6 using the deterioration inhibitor of the present invention and Comparative Examples 1 and 2 using a commercially available copper damage inhibitor were compared with Comparative Example 3 in which neither was used. As a result, it showed a high copper damage prevention effect. However, as can be seen by comparing Examples 5 and 6 with Comparative Examples 1 and 2, there was no significant difference in the effect.
Moreover, as can be seen by comparing each example, it was also confirmed that the effect of preventing copper damage is improved by increasing the amount of the deterioration inhibitor of the present invention.

4. Confirmation of strength improvement effect of molded product 4-1. Production of pellets (Example 11)
First, board pulp (manufactured by Howe Sound Pulp and Paper) was impregnated with water overnight so that the solid content was 50 parts by mass, and then pulverized and dried to prepare cellulose fibers.
Next, pellets were obtained in the same manner as in the above example, except that 2.5 parts by mass of deterioration inhibitor 1, 4.1 parts by mass of cellulose fiber, and 93.4 parts by mass of polypropylene were mixed. rice field.

(Example 12)
2.5 parts by mass of deterioration inhibitor 1, 3.0 parts by mass of copper damage inhibitor 1, 4.1 parts by mass of cellulose fiber, and 90.4 parts by mass of polypropylene except for mixing the above Pellets were obtained in the same manner as in Examples.
(Example 13)
2.5 parts by mass of deterioration inhibitor 1, 3.0 parts by mass of copper damage inhibitor 2, 4.1 parts by mass of cellulose fiber, and 90.4 parts by mass of polypropylene except for mixing the above Pellets were obtained in the same manner as in Examples.
(Example 14)
Pellets were obtained in the same manner as in the above example, except that 2.5 parts by mass of deterioration inhibitor 2, 4.1 parts by mass of cellulose fiber, and 93.4 parts by mass of polypropylene were mixed.

(Comparative Example 11)
Pellets were obtained in the same manner as in the above example, except that 4.1 parts by mass of cellulose fiber and 95.9 parts by mass of polypropylene were mixed.
(Comparative Example 12)
Pellets were obtained in the same manner as in the above example, except that 3.0 parts by mass of deterioration inhibitor 1, 4.1 parts by mass of cellulose fiber, and 92.9 parts by mass of polypropylene were mixed.
(Comparative Example 13)
Pellets were obtained in the same manner as in the above example, except that 3.0 parts by mass of deterioration inhibitor 2, 4.1 parts by mass of cellulose fiber, and 92.9 parts by mass of polypropylene were mixed.

4-2. Evaluation of MD flexural modulus First, the obtained pellets were molded with an injection molding machine (manufactured by Sumitomo Heavy Industries, "iM18") at a melting point of 180 to 230 ° C. and a mold of 50 ° C., ASTM No. 4 (1.6 mm thick ) was prepared.
Next, each sample piece was placed on a flat plate made of tetrafluoroethylene (Sample A) and sandwiched between copper plates (Sample B) and left in an oven at 140° C. for one day.

After one day, the flexural modulus in the direction (MD direction) in which the molten resin flows from the gate of each sample piece to the injection molding die was measured. AUTO GRAPH AGS-X type (manufactured by Shimadzu Corporation) was used as a measuring machine.

4-3. Evaluation of fibrillation properties First, the obtained pellets were sandwiched between polyethylene terephthalate sheets and pressed at 160°C to a thickness of 1 mm. Next, 1 cm ² of the central part was cut out, wrapped in a metal mesh, and after the resin was extracted with hot xylene, the cellulose fibers remaining on the wire mesh were dried. After that, the sample was observed with an SEM at a magnification of 5000 times, and the sample was photographed at three points at random to evaluate the defibration property according to the following evaluation criteria.
A: Unfibrillated fibers with a fiber diameter of 5 μm or more could not be observed in the observation field.
◯: One or more unfibrillated fibers having a fiber diameter of 5 µm or more and less than 10 µm were confirmed in the observation field.
x: One or more unfibrillated fibers with a fiber diameter of 10 µm or more were confirmed in the observation field.
The above results are shown in Table 2 below.

As shown in Table 2, in Examples 11 to 14 using the deterioration inhibitor of the present invention, compared with Comparative Example 11 in which neither the deterioration inhibitor of the present invention nor the commercially available copper damage inhibitor was used. , the disentanglement property of cellulose fibers was improved, and the MD bending elastic modulus of the molded product was increased.
On the other hand, in Comparative Examples 12 and 13, in which only the commercially available copper damage inhibitor was used, as in Comparative Example 11, the fibrillation properties of the cellulose fibers were lowered, and the MD flexural modulus of the molded article was also lowered.
The above results show that the degradation inhibitor of the present invention has a defibration effect on cellulose fibers, and that the commercially available copper damage inhibitor does not have a fibrillation effect on cellulose fibers. Conceivable.

(Comparative Example 11)
Pellets were obtained in the same manner as in the above example, except that 4.1 parts by mass of cellulose fiber and 95.9 parts by mass of polypropylene were mixed.
(Comparative Example 12)
Pellets were obtained in the same manner as in the above example, except that 3.0 parts by mass of copper damage inhibitor 1, 4.1 parts by mass of cellulose fiber, and 92.9 parts by mass of polypropylene were mixed.
(Comparative Example 13)
Pellets were obtained in the same manner as in the above example, except that 3.0 parts by mass of copper damage inhibitor 2, 4.1 parts by mass of cellulose fiber, and 92.9 parts by mass of polypropylene were mixed.

Claims (10)

A deterioration inhibitor capable of suppressing deterioration of polyolefin due to metal ions,
(Meth) comprising a first structural unit based on an acrylic acid alkyl ester and a second structural unit based on an acrylic monomer having an amide group,
A deterioration inhibitor characterized by having a weight average molecular weight of 5,000 to 100,000. The deterioration suppressing agent according to claim 1, wherein the alkyl group of the first structural unit has 6 to 18 carbon atoms. The deterioration inhibitor according to claim 1 or 2, wherein the first structural unit accounts for 25 to 50 mass% of all structural units constituting the deterioration inhibitor. The deterioration inhibitor according to any one of claims 1 to 3, wherein the second structural unit accounts for 50 to 75 mass% of all structural units constituting the deterioration inhibitor. The deterioration inhibitor according to any one of claims 1 to 4, wherein the metal ion is at least one of copper ion, manganese ion and cobalt ion. The deterioration inhibitor according to any one of claims 1 to 5,
A resin composition comprising a polyolefin. 7. The resin composition according to claim 6, wherein the amount of said deterioration inhibitor contained in said resin composition is 1% by mass or more. 8. The resin composition according to claim 6, further comprising cellulose fibers. A molded article comprising a molded article of the resin composition according to any one of claims 6 to 8. 10. The molded article according to claim 9, wherein said molded article is an automobile part.