JP2000336219A - Polyolefin polymer composition for powder molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyolefin polymer composition for powder molding excellent in powder fluidity and hardly causing fogging. SOLUTION: This composition comprises 100 pts.wt. of a powder of a mixture comprising (A) 20-80 wt.% of a polypropylenic polymer and (B) 80-20 wt.% of an olefinic polymer or/and an aromatic vinyl hydrocarbon-conjugated diene copolymer, and (C) 0.5-30 pts.wt. of an acrylic polymer having a glass transition temperature of at least 60 deg.C and an average primary particle size of 0.01-70 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polyolefin polymer composition for powder molding. More specifically, the present invention relates to a polyolefin polymer composition for powder molding which has excellent powder fluidity and does not easily cause fogging.

[0002]

2. Description of the Related Art As a surface layer material for automobile interior parts such as instrument panels and headrests, a powder molding material of a vinyl chloride polymer (hereinafter, referred to as PVC) composition is mainly used. However, these car interiors
For example, since the surface layer is made of PVC, the inner foam layer is made of polyurethane foam, and the core material is made of polyolefin and a plurality of materials, it has been desired in recent years to integrate the inner and outer layer materials so that they can be easily separated from the viewpoint of recycling. Became. Therefore, for the surface layer, PVC has been an excellent material that has been well balanced in terms of performance and cost.
For convenience of separation, a change to a polyolefin-based polymer has been proposed (Japanese Patent Application Laid-Open Nos. 5-1183 and 5-2).
No. 79484). Also, the use of polyolefin-based polymers for foamed layers has begun to be studied. However, the use of the polyolefin polymer for the surface layer according to the above proposal has a problem that pinholes are generated in a molded product due to insufficient powder fluidity and heat resistance. In general, it is important that the powder molding material for the surface layer has good powder fluidity and excellent powder characteristics in order to obtain a good molded product. When the powder fluidity deteriorates, not only the thickness of the molded product becomes non-uniform, but also the incidence of molding defects such as pinholes increases. Until now, in order to solve such problems, inorganic fine powder has been added to the polyolefin polymer composition for powder molding for the purpose of playing a role of a roller. However, although a small amount of inorganic fine powder significantly improves the powder characteristics of the powder molding composition in a small amount, it causes a decrease in the physical properties of the molded product and also greatly reduces the melting property of the material polymer itself. In addition, there has been a problem of causing defects such as uneven thickness of the molded product and pinholes. In addition, since only a small amount of inorganic fine powder can be used, if the powder molding composition is stored for a long time in a high-temperature warehouse in summer, the polymer powder will fuse and the powder fluidity will decrease. There was also.
To solve these problems, Japanese Patent Application Laid-Open No. 6-106553 has been proposed.
In the publication, organic fine particles such as a polypropylene-based polymer, a polyethylene-based polymer, and a vinyl chloride-based polymer are used for a powder of a partially crosslinked elastomer of an ethylene / α-olefin-based copolymer and a polyolefin-based polymer. It has been proposed to add However, in the case of the polypropylene-based polymer and the polyethylene-based polymer, when the obtained molded article is mounted in a car, a problem of fogging occurs in which the glass in the car becomes cloudy with a volatile component. Practicality was still insufficient, such as poor compatibility with the polyolefin-based polymer and lowering the mechanical strength of the molded product.

[0003]

SUMMARY OF THE INVENTION Under these circumstances,
The present inventors have improved the powder fluidity, and do not cause fogging, as a result of repeated studies on the realization of a polyolefin polymer composition for powder molding that can obtain a high-strength molded article, specific results, It has been found that the above problems can be solved by blending the acrylate polymer fine particles, and the present invention has been completed.

[0004]

That is, the present invention provides:
100 parts by weight of a powder of a mixture of (A) 20 to 80% by weight of a polypropylene polymer and (B) 80 to 20% by weight of an olefin polymer and / or an aromatic vinyl hydrocarbon-conjugated diene copolymer; And (C) a powder-forming polyolefin polymer composition comprising 0.5 to 30 parts by weight of an acrylate polymer having a glass transition temperature of 60 ° C. or higher and a primary average particle size of 0.01 to 70 μm, Is provided.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The polypropylene polymer used as the component (A) in the present invention is a propylene homopolymer or a copolymer of 50% by weight or more of propylene and another α-olefin having 2 to 12 carbon atoms. Here, propylene and α having 2 to 12 carbon atoms
-Copolymers with olefins include random copolymers, alternating copolymers and block copolymers, and are often produced by polymerization using a Ziegler-Natta catalyst or the like. Examples of such α-olefin include ethylene, butene-1, 4-methyl-pentene-1, octene-1 and the like. The propylene-based polymer is not particularly limited, but may be JIS K7210.
The melt flow rate (hereinafter referred to as MFR) is preferably 5 g / min or more (230 ° C., 2.16 kg load), and more preferably 20 g / min or more. MFR of polypropylene-based polymer is 5 g /
If it is smaller than min, the meltability is poor and pinholes may easily occur.

As the component (B) in the composition of the present invention,
Olefin polymer or / and aromatic vinyl hydrocarbon-
A conjugated diene copolymer is used. Here, the olefin polymer is an olefin homopolymer or a copolymer,
Excludes the polypropylene polymer of component (A). That is, an ethylene homopolymer or an ethylene polymer which is a copolymer of ethylene and another vinyl monomer (excluding propylene in an amount of 50% by weight or more), polybutene-1, poly4-methylpentene-1 And the like.
Specific examples of the ethylene polymer include high density polyethylene, medium density polyethylene, low density polyethylene, linear low density polyethylene, ethylene-butene-1 copolymer,
Ethylene-hexene-1 copolymer, ethylene-heptene-1 copolymer, ethylene-octene-1 copolymer, ethylene-4-methylpentene-1 copolymer, ethylene-vinyl acetate copolymer, ethylene-acryl Examples include an acid copolymer, an ethylene-alkyl acrylate copolymer, an ethylene-methacrylic acid copolymer, and an ethylene-methacrylic acid alkyl ester copolymer. Preferred as the ethylene-based polymer are linear low-density polyethylene, ethylene-butene-1 copolymer, ethylene-hexene-1 copolymer, ethylene-heptene-1 copolymer, and ethylene-octene-1 copolymer. Such as coalescence. A preferred olefin polymer has an MFR of 5 g / min or more (190 ° C., 2.16 kg load).
Is more preferably 20 g / min or more. When the MFR of the olefin polymer is less than 5 g / min, the meltability is poor and pinholes may easily occur.

As the component (B) in the composition of the present invention,
An aromatic vinyl hydrocarbon-conjugated diene copolymer (hereinafter, referred to as an aromatic vinyl copolymer) may be used. Examples of the aromatic vinyl hydrocarbon include styrene, α-methylstyrene, 1-vinylnaphthalene, 2-vinylnaphthalene, 3-methylstyrene, 4-propylstyrene,
Cyclohexylstyrene, 4-dodecylstyrene, 2-
Ethyl-4-benzylstyrene, 4- (phenylbutyl) styrene and the like. Of these, styrene or α-methylstyrene is preferred. Examples of the conjugated diene include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene,
2-methyl-1,3-pentadiene, 1,3-hexadiene, 4,5-diethyl-1,3-octadiene, 3-
Butyl-1,3-octadiene, chloroprene and the like. Of these, 1,3-butadiene is preferred.

In the present invention, the aromatic vinyl copolymer may be one obtained by hydrogenating a double bond of a conjugated diene monomer portion of an aromatic vinyl hydrocarbon-conjugated diene copolymer. included. That is, a hydrogenated aromatic vinyl hydrocarbon-conjugated diene copolymer can also be used as the component (B) in the present invention. Examples of such hydrogenated copolymers include styrene-butadiene-
Hydrogenated styrene block copolymer (commonly known as styrene / ethylene / butylene / styrene copolymer or SEBS
It is written. ), Hydrogenated styrene-isoprene-styrene block copolymer (commonly referred to as styrene-ethylene-propylene-styrene copolymer or SEPS), hydrogenated styrene-butadiene copolymer, and the like. Preferred aromatic vinyl copolymers have an MFR of 0.1.
Those having an MFR of 5 g / min or more (at 230 ° C. and a load of 2.16 kg) are more preferable. When the MFR of the olefin polymer is less than 5 g / min, the meltability is poor and pinholes may easily occur. In the present invention, the use ratio of the component (A) to the component (B) is 20/80 to 80/20 by weight, preferably 40/60 to 60/40. When the use ratio of the component (A) is less than 20% by weight, there is a risk that the mechanical strength of the obtained molded product is reduced, while the weight ratio is 80% by weight.
If it is larger, the hardness of the obtained molded article may increase.

The acrylate copolymer used as the component (C) of the composition of the present invention has a glass transition temperature (hereinafter, referred to as a glass transition temperature).
Also called Tg. ) Is 60 ° C. or more and the primary average particle size is 0.01 to 70 μm. Tg of component (C)
Can be determined by a differential thermal analyzer, and is preferably 70
C. or higher, more preferably a temperature higher than 80.degree. T
If g is lower than 60 ° C., the fluidity of the powder in the process of increasing the temperature during molding tends to deteriorate. When the acrylate copolymer has a core-shell structure, the Tg of the polymer constituting the shell may satisfy the above requirements. That is, if the Tg of the shell polymer is 60 ° C. or higher, preferably 70 ° C. or higher, and more preferably a temperature higher than 80 ° C., the Tg of the core polymer may be −22 ° C., for example, polyethyl acrylate. It may be low. The primary average particle diameter of the component (C), that is, the average diameter of a single particle, is determined by dispersing an acrylate-based copolymer powder in water and setting the oscillation frequency to 50 k.
The suspension was allowed to stand for 1 minute after being placed on an ultrasonic shaker at 3 Hz, and the suspension was allowed to stand for 3 minutes to determine the integrated particle size distribution by the centrifugal sedimentation turbidity method. The preferred primary average particle size of the component (C) is 0.3 to 30 μm.
If the primary average particle size is smaller than 0.01 μm, color unevenness tends to occur in the molded product, while if it is larger than 30 μm, the powder fluidity of the powder molding composition may be insufficient.

In the present invention, the main components of the composition of the acrylate copolymer (in the case of the core-shell structure, the main components of the shell polymer) are alkyl alcohol having 1 to 8 carbon atoms and (meth) acrylic acid [ (Meth) may be described when referring to acrylic acid and methacrylic acid. ] Is an ester of Specific examples thereof include methyl methacrylate (Tg in the case of a homopolymer (the same applies hereinafter): 105 ° C.),
Ethyl methacrylate (65 ° C), isopropyl methacrylate (81 ° C), t-butyl methacrylate (10
7 ° C.), cyclohexyl methacrylate (56 ° C.), phenyl methacrylate (110 ° C.), etc., and these monomers account for 50% by weight or more based on all monomers forming the polymer. Things. If it is lower than 50% by weight, the glass transition temperature of the copolymer may be lower than 60 ° C.

Further, as a second component of the acrylate polymer in the present invention, if necessary, another monomer may be used as a comonomer in an amount of less than 50% by weight. Examples of these monomers include aromatic vinyl compounds such as styrene, vinyltoluene and α-methylstyrene;
Vinyl cyanide compounds such as (meth) acrylonitrile and vinylidene cyanide; vinyl ester compounds such as vinyl acetate and vinyl propionate; vinyl ether compounds such as ethyl vinyl ether, methyl vinyl ether and hydroxybutyl vinyl ether; α-hydroxyethyl (meth) acrylate; 3-hydroxybutyl (meth) acrylate, butoxyethyl (meth) acrylate or the like, a functional group-containing acrylic acid or alkyl methacrylate compound such as 2-hydroxyethyl fumarate;
Dibasic acid ester compounds such as monobutyl malate; and vinyl chloride. Among these acrylate-based copolymers, methyl methacrylate is 5%.
A methacrylate copolymer containing 0% by weight or more is preferable.

In order to produce the fine particles of the acrylate polymer (C) as described above, emulsion polymerization (including seeded emulsion polymerization) and fine suspension polymerization (including seeded fine suspension polymerization) ) Or a suspension polymerization method. The amount of the component (C) in the composition of the present invention is 0.5 to 30 parts by weight, preferably 1 to 10 parts by weight, per 100 parts by weight of the powder of the mixture of the components (A) and (B). is there. If the amount is less than 0.5 part by weight, there is a risk that the powder fluidity may not be sufficiently improved, while if the amount is more than 30 parts by weight, the mechanical strength of the molded article may be reduced.

The composition of the present invention includes the above (A) and (B)
And in addition to the component (C), if necessary, an antioxidant,
UV absorbers, antistatic agents, flame retardants, pigments, slip agents, dispersants, fillers, etc. can be added,
Known plasticizers and the like can be added within a range that does not impair the tackiness, moldability, and the like. The composition of the present invention is completed by uniformly mixing the above-mentioned components. For producing such a composition, any method may be adopted as long as a good dispersion of each component is obtained, and there is no particular limitation. Usually, the target polymer is melt-kneaded by a closed mixer such as a Henschel mixer, a Banbury mixer, a pressure kneader, or a single-screw extruder or a twin-screw extruder used in the rubber / polymer industry. Further, as a kneading method, a method in which a polymer component and various additives are charged in a first stage by an extruder having a multi-stage addition port, and a liquid component such as a plasticizer is injected in a second stage can be adopted.

When a mixing method involving melting of a polymer component such as an extruder is employed among the various mixing methods described above, a pulverization step is then carried out to improve the powder flowability of the composition. preferable. Such a pulverization step can be prepared by pulverization using a pulverizer such as a turbo mill, a roller mill, a ball mill, a centrifugal pulverizer, or a pulperizer. The powdery polyolefin polymer composition thus obtained preferably has an average particle size of 50 to 500 μm, preferably 100 to 300 μm. Here, the average particle size of the polyolefin polymer composition is determined by JI
Integral particle size distribution curve by sieve analysis using S standard sieve is 50
It is the particle size corresponding to the aperture indicating the weight%. If the average particle size is less than 50 μm, the efficiency of the pulverization process is low, and the powder tends to agglomerate during storage. If it exceeds 500 μm, the texture of the molded product becomes rough. Is more likely to occur. The polyolefin polymer composition of the present invention can be applied to various powder molding methods such as powder slush molding, fluid immersion molding or powder rotational molding, and particularly for instrument melt panels, headrests, console boxes, door trims, armrests and the like. It can be suitably used as a powder molding material for the surface layer of automobile interior parts.

[0015]

The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these examples. Acrylate polymers 1 to 4 were prepared by the methods of the following production examples. Acrylate polymer production example 1 Water 2 was placed in a stainless steel reactor equipped with a stirrer and a jacket.
00 parts by weight, 1.0 part by weight of potassium oleate and 0.6 part by weight of potassium persulfate were added and degassed, and 50 parts by weight of methyl methacrylate, 50 parts by weight of stearyl acrylate and 0.15 parts by weight of t-dodecyl mercaptan were added. I charged. The temperature of the reactor was raised to maintain the reaction temperature at 60 ° C. to carry out the polymerization reaction. The polymerization rate was tracked by the change in the solid concentration of the reaction liquid sampled in a small amount, and after confirming that the polymerization rate was 92%, the system was cooled. The reaction was completed to obtain a latex. The latex was dried with a spray dryer in a nitrogen stream at 170 ° C. to obtain an acrylate polymer 1. Acrylate polymer 1
Are shown in Table 1.

Preparation Example 2 of Acrylate Polymer In a stainless steel reactor equipped with a stirrer and a jacket, 0.5 parts by weight of polyvinyl alcohol and 0.1% of methyl cellulose were added.
200 parts by weight of water in which 5 parts by weight were dissolved were added and degassed, 0.2 parts by weight of azobisisobutylnitrile and 100 parts by weight of methyl methacrylate were charged, and the temperature of the reactor was raised to 55 ° C. by heating. The polymerization reaction was carried out, and the polymerization rate was tracked based on the solid content concentration of the reaction liquid sampled in a small amount. After the polymerization rate was confirmed to be 90%, the reaction was completed by cooling, and a slurry was obtained. After dehydrating the slurry, the slurry was dried with a fluidized drier at 170 ° C. using nitrogen to obtain an acrylate polymer 2. Table 1 shows the properties of the acrylate polymer 2.

Acrylate-based polymer production example 3 An acrylate-based polymer production example except that 50 parts by weight of methyl methacrylate and 50 parts by weight of stearyl acrylate were used instead of 50 parts by weight of methyl methacrylate and 50 parts by weight of styrene as monomers. In the same manner as in Example 1, acrylate polymer 3 was obtained. Table 1 shows the properties of the acrylate polymer 3.

Preparation Example 4 of Acrylate Polymer Water 2 was introduced into a stainless steel reactor equipped with a stirrer and a jacket.
100 parts by weight and degassed, and methyl methacrylate 50
Parts by weight, 50 parts by weight of n-butyl acrylate, 1.0 part by weight of sodium dodecylbenzenesulfonate, 1.5 parts by weight of stearyl alcohol and 0.3 parts by weight of benzoyl peroxide, and after stirring and mixing at room temperature for 30 minutes, The mixture was homogenized by a homomixer, transferred to a stirrer and a jacketed stainless steel polymerization vessel, and polymerized at a polymerization temperature of 60 ° C. for 5 hours. After confirming the polymerization rate of 90% by sampling, the reaction was completed by cooling, and a latex was obtained. The latex was dried with a spray dryer in a nitrogen stream at 170 ° C. to obtain an acrylate polymer 4. Acrylate polymer 4
Are shown in Table 1.

[0019]

[Table 1]

Examples 1 to 5, Comparative Examples 1 to 3 60 parts by weight of a polypropylene polymer (J709, manufactured by Grand Polymer Co., Ltd., MFR = 55 g / 10 min.), A linear low-density polyethylene polymer (Novatech LL)
UJ790, manufactured by Nippon Polychem Co., Ltd., MFR = 50 g
/ 10 min. ) 20 parts by weight, SEBS (Tuftec H
1042, manufactured by Asahi Kasei Kogyo Co., Ltd., MFR = 30 g / 10
min. ) 20 parts by weight and fine powder of the kind and amount shown in Table 2 were mixed with a Henschel mixer, and then mixed with a twin screw extruder (TEM-35B, manufactured by Toshiba Machine Co., Ltd., cylinder diameter 3).
5 mm, barrel temperature 200 ° C.)
A pellet having a length of 3 mm was obtained and then pulverized by a turbo mill to obtain a powdery polyolefin polymer composition. The obtained polyolefin polymer composition was evaluated for powder fluidity by the following method, and for meltability in powder molding, non-fogging property and tensile strength of a molded product. Table 2 shows the results.

(1) Powder flowability The powdery polyolefin polymer composition 100 at a temperature of 23 ° C. was measured using a bulk specific gravity measuring device specified in JIS K 6721.
Measure the fall time of the cc. The shorter the fall time, the better the powder fluidity. If the time is longer than 30 seconds, the fluidity is poor, and the thickness of the sheet may be uneven. Further, the polyolefin polymer composition was placed in an oven at 50 ° C. for 30 minutes, and it was confirmed that the composition was heated to 50 ° C., and immediately after that, the drop time of 100 cc of the composition was measured in the same manner as above. When the powder flowability in the heated state is good, the powdery composition is adhered to the mold during molding in the actual machine, the excess composition is received in the reservoir, and the powder composition is repeatedly supplied to the mold. There is a tendency for the mold details to be well distributed.

(2) Meltability The slush molding is performed three times using the powdery polyolefin polymer composition, and the uniformity of the sheet obtained is examined. That is, a 150 × 100 × 3 mm nickel mold was heated to 280 ° C., 260 ° C., and 240 ° C., respectively.
The powdered thermoplastic polymer composition was placed on each side for 10 seconds, and then inverted to remove excess powder that had not adhered.
Hold for 0 seconds to gel. Next, the mold is water-cooled,
When the temperature of the mold reached 60 ° C., the gelled sheet was peeled off, the sheet thickness and the state of pinholes on the sheet surface were examined, and evaluated by the following symbols. It is so good that there is no pinhole. ：: No unevenness in the sheet thickness was observed, and there was almost no pinhole. Δ: There are slight sheet thickness unevenness and pinholes. ×: There is unevenness in the sheet thickness, and there are considerable pinholes.

(3) Non-fogging properties A sheet obtained by slush molding was cut out into a circular shape having a diameter of 70 mm, and a fogging tester (Suga Test Machine Co., Ltd.)
Test) under the following conditions. Subsequent haze values were determined. The lower the haze value, the better the non-fogging properties. Heating oil temperature × time: 110 ° C. × 5 hours Cooling plate temperature: 30 ° C. (4) Tensile strength In the same manner as in the melting test, 280 ° C.
A sintered sheet having a thickness of 1 mm is prepared under the condition of 10 seconds. A JIS K 6301 type 1 test piece is punched from this sheet. Next, the tensile strength is measured based on the method of JIS K7113.

Comparative Example 4 The procedure of Example 1 was repeated except that the polypropylene polymer was 86 parts by weight and the linear low-density polyethylene polymer and SEBS were each 7 parts by weight. Table 2 shows the evaluation results of the obtained polyolefin polymer composition for powder fluidity, meltability, and non-fogging property. Comparative Example 5 The same procedure as in Example 1 was carried out except that the polypropylene polymer was 14 parts by weight, the linear low-density polyethylene polymer was 60 parts by weight, and the SEBS was 26 parts by weight. Table 2 shows the evaluation results of the obtained polyolefin polymer composition for powder fluidity, meltability, and non-fogging property.

[0025]

[Table 2]

Note * 1: Methyl methacrylate polymer, Zeon F-32
5. Tg: 105 ° C., average particle size: 0.8 μm, manufactured by Zeon Corporation. * 2: Silica, Aerosil A200, manufactured by Nippon Aerosil Co., Ltd., average particle size 0.016 μm. * 3: Polypropylene, Lanco wax PP1362
D, manufactured by Sansei Co., Ltd., average particle size is 3.5 μm.

Examples 1 to 5 satisfying the requirements of the present invention were all excellent in powder fluidity, meltability and non-fogging properties. In particular, Examples 2 to 4 show that when the Tg of the acrylate polymer is higher than 80 ° C, the powder fluidity of the polyolefin polymer composition during heating is particularly good. However, in Comparative Example 1 in which silica was used as the fine powder of the component (C), the fine powder conformed to the requirements of the present invention, but was an inorganic powder, so that the polyolefin polymer composition for powder molding was used. Was inferior in meltability and the tensile strength of the molded sheet was low. In Comparative Example 2 using polypropylene as the fine powder, the powder fluidity and the non-fogging property were poor even if the average particle size of the present invention was satisfied. Further, even if the particle size and glass transition temperature of the fine powder conformed to the requirements of the present invention, if the amount was too small, the powder fluidity deteriorated (Comparative Example 3). In Comparative Example 4 in which the ratio of the component (A) is large and the ratio of the component (B) is small in light of the provisions of the present invention,
A molded product having poor meltability and being hard and having high tensile strength was obtained as a result. In Comparative Example 5 in which the proportion of the component (A) was small and the proportion of the component (B) was small in light of the provisions of the present invention, a molded article having slightly poor meltability and low tensile strength was obtained.

[0028]

According to the present invention, there is provided a polyolefin polymer composition for powder molding which has good powder flowability and is less likely to cause fogging. The united molded product is more convenient for recycling.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Satoshi Iwabuchi 2-1-1, Yakko, Kawasaki-ku, Kawasaki-shi, Kanagawa F-term in the ZEON Kasei Co., Ltd. Kawasaki Laboratory (reference) 4F205 AA03 AA11 AA13 AA21 AC04 GA12 GB01 GC04 GE03 GE24 4J002 AC02X AC08X AC11X BB05X BB06X BB07X BB08X BB10X BB12W BB14W BB15W BB17X BC01X BC034 BC044 BC05X BC054 BC064 BC074 BC08X BC084 BC09X BC094 BD044 BG043 BG053 BB05W BP05 BB05X BP053 BH024BN

Claims (1)

[Claims] (A) a polypropylene-based polymer 20 to 8
0% by weight and (B) 80 to 20% by weight of an olefin polymer or / and an aromatic vinyl hydrocarbon-conjugated diene copolymer
And (C) a glass transition temperature of 60 ° C. or more and a primary average particle size of 0.01 to 7 parts by weight.
A polyolefin polymer composition for powder molding, comprising 0.5 to 30 parts by weight of an acrylate polymer having a particle size of 0 μm.