JPH0616901A - Polyacetal resin composition - Google Patents

Abstract

(57) [Summary] [Object] To provide a polyacetal resin composition excellent in impact resistance, mechanical strength, and pigment coloring. [Structure] A composite rubber comprising a polyorganosiloxane component and an alkyl (meth) acrylate rubber component, and one or more vinyl monomers graft-polymerized to have a number average particle diameter of 0.01 to 0.07 μm and 0.10. μm
A resin composition obtained by mixing a graft composite rubber (A) having a larger particle volume of 20% or less of the total particle volume and a polyacetal resin (B).

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a polyacetal resin composition excellent in impact resistance, mechanical strength and pigment coloring.

[0002]

Demand for polyacetal resins has been increasing in recent years because of their excellent mechanical properties, fatigue properties and friction and wear properties. However, the polyacetal resin has low impact resistance represented by notched impact strength and the like, and its use as a strength material has been limited.

Japanese Patent Application Laid-Open No. 59-136343 discloses a polyoxymethylene having a two-layer structure having a particle size of 10 to 10.
It is disclosed that a resin composition containing a 0 μm acrylic multilayer polymer has excellent impact resistance. In addition, JP-A-2-
Japanese Patent No. 294351 discloses that a resin composition obtained by adding a multi-layer polymer in which the outermost layer is a polyacetal layer to polyoxymethylene has excellent impact resistance.

On the other hand, various rubbers have been proposed for the purpose of improving the impact resistance of various resins. For example, JP-A-60
-252613, focusing on the decrease in Tg and elastic modulus of the rubber layer, it is considered to use a polyorganosiloxane rubber having both a low Tg and a low elastic modulus as a rubber source of an impact resistant resin. There is. However, this method cannot improve the matte appearance of the surface derived from polyorganosiloxane rubber. Further, when such a rubber is used, a large particle size is used because impact resistance is lowered when the particle size is small.

In Japanese Patent Laid-Open No. 63-69859, a vinyl monomer is graft-polymerized on a composite rubber composed of a polyorganosiloxane rubber and a poly (meth) acrylic rubber in order to improve the surface appearance of a resin molded product. There has been proposed a composite rubber-based graft copolymer. Further, JP-A-62-280210 discloses a graft polymer composed of a core of crosslinked silicone rubber, a first shell of crosslinked acrylate rubber, and a second shell composed of a graft component of vinyl polymer. Proposed. Further, JP-A-64-6012 proposes a graft polymer obtained by graft-polymerizing an ethylenically unsaturated monomer onto a rubber composed of a core such as a crosslinked acrylate rubber and a shell of polyorganosiloxane. .

[0006]

However, Japanese Patent Application Laid-Open No. 59-59
The resin composition of Japanese Patent No. 136343 does not have satisfactory performance as an impact resistant resin because the degree of improvement in impact resistance is small and the molding resin has anisotropy. In addition, Japanese Patent Laid-Open No. 2-
Since the resin composition of Japanese Patent No. 294351 has a large amount of the multilayer polymer added, the flexural modulus of the resin composition is lowered, and the original properties of the polyacetal resin are lost.

On the other hand, JP-A-62-280210 and JP-A-64-280210
Although the specification of the 6012 publication refers to a graft polymer having a number average particle diameter of 0.05 μm or more, it is 0.
Only those with a large particle size of 15 to 0.42 μm are described, and
It does not suggest any concrete means for producing a product having a size of 10 μm or less. Further, JP-A-63-69859 only discloses a composite rubber-based graft copolymer having a particle size of more than 0.08 μm. That is, conventionally only a graft rubber of substantially 0.08 μm or more is known as a rubber for improving impact resistance, and when a rubber having such a large particle size is added to a resin together with a pigment, a pigment of a resin composition Poor colorability and low industrial value.

It is an object of the present invention to provide a polyacetal resin composition which overcomes the above problems in the prior art, retains the excellent properties of the polyacetal resin, and has excellent impact resistance and pigment coloring properties. .

[0009]

Means for Solving the Problems The inventors of the present invention have made earnest studies on the relationship between the particle size of the graft copolymer and the coloring property when a pigment is added, and as a result, surprisingly, it was found that a polymer having a small particle size is used. When a composite rubber having a fine particle size of a polyorganosiloxane rubber and a poly (meth) acrylate rubber is produced using an organosiloxane rubber, a resin composed of a graft copolymer and a polyacetal resin obtained from this composite rubber The present inventors have found that the composition exhibits excellent impact resistance and, at the same time, exhibits good pigment coloring.

The gist of the present invention is that the composite rubber comprising a polyorganosiloxane component and an alkyl (meth) acrylate rubber component is graft-polymerized with one or more vinyl monomers and has a number average particle diameter of 0.01. ~ 0.07μ
and the volume of particles larger than 0.10 μm is
20% or less of graft composite rubber (A) and polyacetator
And a resin composition (B).

The graft composite rubber (A) used in the present invention has a number average particle diameter in the range of 0.01 to 0.07 μm, and the volume of particles larger than 0.10 μm is 20% or less of the total volume of the graft composite rubber. Is. When the number average particle diameter is smaller than 0.01 μm, the impact resistance of the molded product obtained from the resin composition deteriorates. When the number average particle size is larger than 0.07 μm, the light scattering of visible light by the particles becomes large, and the pigment coloring property of the molded product deteriorates. The volume of particles larger than 0.10 μm is preferably 10% or less.

In the graft composite rubber (A) of the present invention, a vinyl monomer is graft-polymerized onto the composite rubber in a state where the polyorganosiloxane component and the polyalkyl (meth) acrylate rubber component cannot be substantially separated. It has a structured structure. This composite rubber can take various forms, such as a mixture in which both components are almost uniformly mixed and dispersed, a form in which a polyalkyl (meth) acrylate rubber component is dispersed in a polyorganosiloxane in a salami structure, The organosiloxane and the polyalkyl (meth) acrylate may have a layered form or the like, and these forms may be appropriately mixed. As an example of the layered morphology, a polyalkyl (meth) acrylate is used as a core, and a first layer of polyorganosiloxane and a second layer of polyalkyl (meth) acrylate are present on the core, or a polyorganosiloxane is used as a core. Polyalkyl (meth) acrylate on top
And a second layer of polyorganosiloxane is present.

In the present invention, as the raw material of the polyorganosiloxane, for example, a mixture of diorganosiloxane and a siloxane-based graft crossing agent or a mixture of a siloxane-based crosslinking agent is used. The mixture is emulsified with an emulsifier and water, and the latex is atomized using a homomixer that atomizes by a shearing force by high-speed rotation or a homogenizer that atomizes by a jet output from a high-pressure generator, and then hot dodecyl A polyorganosiloxane can be obtained by dropping the solution into an aqueous solution of benzenesulfonic acid at a constant rate for polymerization and then neutralizing dodecylbenzenesulfonic acid with an alkaline substance.

The size of the polyorganosiloxane is not particularly limited, but the number average particle diameter is 0.003 to 0.06 μm, and the volume of particles larger than 0.10 μ is preferably 20% or less of the total particle volume. Such a polyorganosiloxane having a small size and a narrow particle size distribution is polymerized by dropping a finely divided latex into an aqueous solution of an acid catalyst such as dodecylbenzenesulfonic acid having a low concentration of 50 ° C. or higher at a minute speed. Can be obtained by

Examples of the organosiloxane that constitutes the organosiloxane-based mixture include various organosiloxane-based cyclic compounds having 3 or more membered rings, and those having 3 to 6 membered rings are preferable. Specifically, hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, trimethyltriphenylcyclotrisiloxane, tetramethyltetraphenylcyclotetrasiloxane, octaphenylcyclotetrasiloxane, etc. These may be used alone or in admixture of two or more. The amount of these used is 50% by weight or more, preferably 70% by weight or more, in the organosiloxane mixture.

The siloxane-based crosslinking agent is a trifunctional or tetrafunctional silane-based crosslinking agent such as trimethoxymethylsilane, triethoxyphenylsilane, tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, tetra. Butoxysilane or the like is used.
In particular, a tetrafunctional crosslinking agent is preferable, and among these, tetraethoxysilane is most preferable. The amount of the cross-linking agent used is 0 to 30% by weight, preferably 0.5 to 10% by weight in the organosiloxane mixture.

As the siloxane-based graft crossing agent, compounds capable of forming a unit represented by the following formula are used.

[0018]

[Chemical 1]

In the above formula, R ¹ is a methyl group, an ethyl group, a propyl group or a phenyl group, R ² is a hydrogen atom or a methyl group, n is 0, 1 or 2, and p is a number from 1 to 6. .

A unit of formula (I-1) may be formed (meta).
Acryloyloxysiloxane has a high grafting efficiency and thus can form an effective graft chain, and is advantageous in that it exhibits impact resistance.

Methacryloyloxysiloxane is particularly preferred as a unit capable of forming the unit of the formula (I-1). Specific examples of methacryloyloxysiloxane include β-methacryloyloxyethyldimethoxymethylsilane, γ-methacryloyloxypropylmethoxydimethylsilane, γ-methacryloyloxypropyldimethoxymethylsilane, γ-methacryloyloxypropyltrimethoxysilane, γ-methacryloyloxypropyl. Examples thereof include ethoxydiethylsilane, γ-methacryloyloxypropyldiethoxymethylsilane, and δ-methacryloyloxybutyldiethoxymethylsilane.

Vinyl siloxanes can be mentioned as those capable of forming the unit of the formula (I-2), and specific examples thereof include tetramethyltetravinylcyclotetrasiloxane. Examples of the unit capable of forming the unit of the formula (I-3) include p-vinylphenyldimethoxymethylsilane. Further, as a unit capable of forming the unit of formula (I-4), γ-
Examples thereof include mercaptopropyldimethoxymethylsilane, γ-mercaptopropylmethoxydimethylsilane and γ-mercaptopropyldiethoxymethylsilane. The amount of the graft crossing agent used in the organosiloxane mixture is 10% by weight or less, preferably 0.5 to
It is 5% by weight.

As the emulsifier, anionic emulsifiers are preferable, and sodium alkylbenzene sulfonate, sodium lauryl sulfonate, sodium sulfosuccinate,
An emulsifier selected from sodium polyoxyethylene nonylphenyl ether sulfate and the like is used. Particularly, sulfonic acid-based emulsifiers such as sodium alkylbenzene sulfonate and sodium lauryl sulfonate are preferable. These emulsifiers are used in the range of about 0.05 to 5 parts by weight with respect to 100 parts by weight of the organosiloxane mixture. When the amount used is small, the dispersion state becomes unstable, and it becomes impossible to maintain the emulsified state with a fine particle size. or,
If the amount used is large, the coloring caused by the emulsifier of the polyorganosiloxane becomes severe, which is inconvenient.

The polyorganosiloxane latex thus produced is impregnated with an alkyl (meth) acrylate component consisting of an alkyl (meth) acrylate and a polyfunctional alkyl (meth) acrylate, and then polymerized to give a composite rubber. Obtainable. Examples of the alkyl (meth) acrylate include alkyl acrylates such as methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate and hexyl methacrylate. Acrylate, 2-ethylhexyl meta acrylate,
Alkyl methacrylate such as n-lauryl methacrylate
The use of n-butyl acrylate is particularly preferable. Examples of polyfunctional alkyl (meth) acrylates include allyl methacrylate, ethylene glycol dimethacrylate, propylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,4-
Examples thereof include butylene glycol dimethacrylate, triallyl cyanurate, triallyl isocyanurate and the like. The amount of the polyfunctional alkyl (meth) acrylate used is 0.1 to 20 in the alkyl (meth) acrylate component.
%, Preferably 0.5 to 10% by weight. The alkyl (meth) acrylate and the polyfunctional alkyl (meth) acrylate may be used alone or in combination of two or more kinds.

The above alkyl (meth) acrylate component is added to the latex of the neutralized polyorganosiloxane component, and the usual radical polymerization initiator is allowed to act to polymerize. As the polymerization initiator, a peroxide, an azo initiator, or a redox initiator in which an oxidizing agent and a reducing agent are combined is used. Among these, a redox type initiator is preferable, and a sulfoxylate type initiator in which ferrous sulfate, ethylenediaminetetraacetic acid disodium salt, Rongalite, and hydroperoxide are combined is particularly preferable. A latex of a composite rubber is obtained in which the polyorganosiloxane component and the polyalkyl (meth) acrylate rubber component cannot be substantially separated from each other as the polymerization proceeds.

In the composite rubber composed of polyorganosiloxane and polyalkyl (meth) acrylate according to the present invention, the polyorganosiloxane component is 0.1 to 9
It is about 0% by weight. If it is less than 0.1% by weight, the characteristics of polyorganosiloxane cannot be exhibited and the impact resistance is lowered. On the other hand, when it exceeds 90% by weight, the gloss derived from polyorganosiloxane is lowered and the pigment colorability is also lowered. In carrying out the present invention, octamethyltetracyclosiloxane is used as the dialkylorganosilane,
A repeating unit whose main skeleton is n-butyl acrylate is a polyorganosiloxane rubber obtained by using tetraethoxysilane as a siloxane-based crosslinking agent and γ-methacryloyloxypropyldimethoxymethylsilane as a siloxane-based graft crossing agent. It is preferable to use a composite rubber in which a polyalkyl (meth) acrylate rubber component having is compounded.

The composite rubber thus produced by emulsion polymerization can be graft-copolymerized with a vinyl monomer, and the polyorganosiloxane component and the polyalkyl (meth) acrylate rubber component are different from each other. Since they are so tightly entangled with each other, they cannot be extracted and separated with an ordinary organic solvent such as acetone or toluene. The gel content measured by extracting this composite rubber with toluene at 90 ° C. for 12 hours was 8
It is preferably 0% by weight or more.

As the vinyl-based monomer to be graft-polymerized to this composite rubber, aromatic alkenyl compounds such as styrene, α-methylstyrene and vinyltoluene; methacrylates such as methylmethacrylate and 2-ethylhexylmethacrylate. Acid ester; acrylic acid ester such as methyl acrylate, ethyl acrylate, butyl acrylate;
Vinyl cyanide compounds such as acrylonitrile and methacrylonitrile; epoxy group-containing vinyl compounds such as glycidyl methacrylate; various vinyl-based monomers such as carboxylic acid group-containing vinyl compounds such as methacrylic acid. Are used alone or in combination of two or more.

The graft composite rubber (A) can be obtained by adding a vinyl monomer to the latex of the composite rubber and polymerizing it in a single stage or multiple stages by a radical polymerization technique. After the graft polymerization is completed, the latex is put into hot water in which a metal salt such as calcium chloride or aluminum sulfate is dissolved, salted out and coagulated to separate and recover the graft composite rubber. The ratio of the composite rubber and the vinyl monomer at the time of obtaining the graft composite rubber (A) is 10 to 95% by weight, preferably 20 to 90% by weight of the composite rubber, based on the weight of the obtained graft copolymer. The vinyl monomer is 5 to 90% by weight, preferably 10 to 80% by weight. When the vinyl-based monomer is less than 5% by weight, the dispersion of the graft composite rubber component in the resin composition mixed with another resin is not sufficient, and when it exceeds 90% by weight, the impact strength is lowered, which is preferable. Absent.

The polyacetal resin (B) used in the present invention includes a polyacetal homopolymer and a polyacetal copolymer.

The polyacetal homopolymer is a polymer composed of repeating oxymethylene units (CH2O) and can be obtained by homopolymerizing formaldehyde and trioxane. The polyacetal copolymer is a polymer having a structure in which oxyalkylene units represented by the following formula are randomly inserted in a chain of oxymethylene units.

[0032]

[Chemical 2]

In the above formula, Ro represents hydrogen, an alkyl group or a phenyl group, and m represents a number of 2-6. The insertion rate of oxyalkylene units in the polyacetal copolymer is 0.05 to 50 mol, more preferably 0.1 to 20 mol, based on 100 mol of oxymethylene units.

Examples of oxyalkylene units include oxyethylene units, oxypropylene units, oxytrimethylene units, oxytetramethylene units, oxybutylene units and oxyphenylethylene units. Among these oxyethylene units, a suitable component for enhancing the performance of the polyacetal composition is a combination of oxymethylene units and oxytetramethylene units.

The composition of the graft composite rubber (A) and the polyacetal resin (B) in the resin composition of the present invention is not particularly limited, but the amount of the component (A) is 3 based on the weight of the entire resin composition. It is preferable that the component (B) is 97 to 60% by weight at -40% by weight. Ingredient (A)
When the content is less than 3% by weight, the impact resistance improving effect of the polyacetal resin is insufficient, and when it exceeds 40% by weight, the mechanical strength of the polyacetal resin decreases.

In the resin composition of the present invention, the components (A) and (B) are mechanically mixed using a known apparatus such as a Banbury mixer, a roll mill, a twin-screw extruder or the like, and shaped into pellets. Can be obtained by In the resin composition of the present invention, if necessary, a stabilizer, a plasticizer, a lubricant, a flame retardant,
A pigment or the like can be added. As the stabilizer, an amide compound used as a heat stabilizer, a polyamide, an amidine compound, polyvinylpyrrolidone, a metal salt of a carboxylic acid, a hindered phenol compound used as an antioxidant, a benzo used as a light stabilizer. Examples thereof include triazole compounds and hydroxybenzophenone compounds.

[0037]

EXAMPLES The present invention will be described below with reference to examples and examples. In the Reference Examples and Examples, "parts" and "%" mean "parts by weight" and "% by weight" unless otherwise specified.

In the Reference Example, the particle size of the polyorganosiloxane in the latex was measured by the dynamic light scattering method.
This measurement is a method that utilizes the Brownian motion of particles in latex. When the particles in the latex are irradiated with laser light, they show fluctuations according to the particle diameters, so the particle diameters can be calculated by analyzing these fluctuations. The number average particle size and the particle size distribution were determined using a DLS-700 type manufactured by Otsuka Electronics Co., Ltd.

The swelling degree and gel content of the crosslinked polyorganosiloxane were measured by the following method using polyorganosiloxane obtained by dropping latex into isopropanol and coagulating and drying. That is, the degree of swelling was determined as a value obtained by dividing the weight of toluene occluded by the polyorganosiloxane when the polyorganosiloxane was immersed in toluene at 23 ° C. for 48 hours by the weight of the polyorganosiloxane before immersion. The gel content was determined by extracting polyorganosiloxane in toluene at 23 ° C. for 48 hours.

In the examples, the Izod impact strength is
Measured according to ASTM D 258 (with 1/4 "notch).
The surface hardness was measured by ASTM D785 (Rockwell hardness). Gloss was measured according to ASTM D 523-62 (60 ° specular gloss). Pigment colorability is JIS Z 8729
(L ^* a ^* b ^* object color display method by color system).

The number average particle size of the graft composite rubber and 0.10
The volume fraction of particles of μm or more was determined by observing an ultrathin section sample with a transmission electron microscope. This ultrathin section sample was melt-mixed in an extruder with 90 parts of polymethylmethacrylate and 10 parts of graft composite rubber to form pellets,
The pellets were cut from a press-molded test piece using a microtome.

Reference Example 1 Production of polyorganosiloxane rubber latex SiLx-1: 2 parts of tetraethoxysilane, 0.5 part of γ-methacryloyloxyxypropyldimethoxymethylsilane and 97.5 parts of octamethylcyclotetrasiloxane were mixed,
100 parts of siloxane mixture are obtained. 300 parts of distilled water in which 0.67 part of sodium dodecylbenzenesulfonate was dissolved was added to this, and the mixture was stirred with a homomixer at 10,000 rpm for 2 minutes, and then homogenized at a pressure of 300 kg / cm ² for 2 minutes.
It was passed around to obtain a stable premixed organosiloxane latex.

On the other hand, 10 parts of dodecylbenzenesulfonic acid and 90 parts of distilled water were poured into a separable flask equipped with a cooling condenser to prepare a 10% by weight dodecylbenzenesulfonic acid aqueous solution.

With the aqueous solution heated to 85 ° C., the premixed organosiloxane latex was added dropwise over 2 hours, and after the completion of the addition, the temperature was maintained for 3 hours and cooled. The reaction was then kept at room temperature for 12 hours before caustic soaking.
Polymerization was completed by neutralizing with a da water solution to obtain polyorganosiloxane rubber latex SiLx-1.

The latex thus obtained was
When the solid content was determined by drying at 0 ° C. for 30 minutes, 18.
It was 2% by weight. The swelling degree of this latex is 1
5.6, gel content was 87.6%, number average particle diameter was 0.03 μm, and volume fraction of particles larger than 0.10 μm was 6.8%.

Reference Example 2 Production of Grafted Composite Rubber S-1: 54.9 parts of the latex SiLx-1 obtained in Reference Example 1 was collected,
Place in a separable flask equipped with a stirrer and add distilled water 17
After adding 0 part, a mixed solution of 58.8 parts of butyl acrylate, 1.2 parts of allyl methacrylate and 0.12 part of tert-butyl hydroperoxide was charged and stirred for 30 minutes to impregnate the polyorganosiloxane rubber particles. .
Nitrogen was replaced by passing a nitrogen stream through the separable flask, and the temperature was raised to 60 ° C. When the temperature of the solution reached 60 ° C, 0.001 part of ferrous sulfate, 0.003 part of ethylenediaminetetraacetic acid disodium salt and 0.24 part of Rongalit were dissolved in 10 parts of distilled water to add radical polymerization. Started. The liquid temperature rose to 82 ° C. due to the polymerization of the butyl acrylate mixed liquid. This state was maintained for 1 hour to complete the polymerization of butyl acrylate to obtain a composite rubber latex. After the liquid temperature dropped to 75 ° C, a mixed liquid of 0.12 parts of tert-butylhydroperoxide and 30 parts of methyl methacrylate was added dropwise to this composite rubber latex over 15 minutes, and then the mixture was kept at 70 ° C for 4 hours to obtain a composite rubber. The graft polymerization to was completed. The obtained composite rubber-based graft copolymer latex was gradually dropped into 200 parts of water (25 ° C.) containing 1.5% by weight of calcium chloride, coagulated, separated, washed, and then dried at 75 ° C. for 16 hours. 96.8 parts of a dry powder of the graft composite rubber S-1 was obtained. The number average particle diameter of this graft composite rubber was 0.05 μm, and the volume fraction of particles larger than 0.10 μm was 5.6%.

Reference Examples 3-5 Grafted composite rubber S-2
Production of S-4: Grafted composite rubber S- in the same manner as in Reference Example 2 except that the composition ratio of the latex SiLx-1, butyl acrylate (BA) and allyl methacrylate (AMA) was changed to the values shown in Table 1.
2 to S-4 were obtained.

Reference Example 6 Grafted Silicone Rubber S-5
Production: Grafted silicone rubber S-as in Reference Example 2 except that the composition ratio of latex SiLx-1 was changed to the values shown in Table 1.
Got 5.

Reference Example 7 Production of Grafted Composite Rubber S-6: 39.2 parts of the latex SiLx-1 obtained in Reference Example 1 was sampled and placed in a separable flask equipped with a stirrer, and 182 parts of distilled water was added. After addition, 42.0 parts of butyl acrylate,
Charge a mixed solution of 0.86 part of allyl methacrylate and 0.2 part of tert-butyl hydroperoxide,
The polyorganosiloxane rubber particles were impregnated with stirring for a minute. Nitrogen was replaced by passing a nitrogen stream through the separable flask, and the temperature was raised to 60 ° C. Liquid temperature is 60
When the temperature reached ℃, 0.001 part of ferrous sulfate, 0.003 part of ethylenediaminetetraacetic acid disodium salt, and 0.24 part of Rongalit were dissolved in 10 parts of distilled water, and an aqueous solution was added to initiate radical polymerization. . The liquid temperature rose to 82 ° C. due to the polymerization of the butyl acrylate mixed liquid. This state was maintained for 1 hour to complete the polymerization of butyl acrylate to obtain a composite rubber latex. After the liquid temperature dropped to 75 ° C, a mixed liquid of 0.12 parts of tert-butyl hydroperoxide and 50 parts of methyl methacrylate was added to this composite rubber latex.
Drop over 25 minutes, then hold at 70 ° C for 4 hours,
The graft polymerization on the composite rubber was completed.

The obtained graft composite rubber latex was coagulated, separated, washed and dried in the same manner as in Reference Example 2 to obtain 96.3 parts of a dry powder of the graft composite rubber S-6. The number average particle diameter of this graft composite rubber is 0.05 μm, and it is 0.10 μm.
The volume fraction of particles larger than m was 6.1%.

Reference Example 8 Production of Grafted Composite Rubber S-7: 70.6 parts of the latex SiLx-1 obtained in Reference Example 1 was sampled and placed in a separable flask equipped with a stirrer, and 121 parts of distilled water was added. After addition, 75.6 parts of butyl acrylate,
Charge a mixed solution of 1.54 parts of allyl methacrylate and 0.2 parts of tertiary butyl hydroperoxide, and add 30 parts.
The polyorganosiloxane rubber particles were impregnated with stirring for a minute. Nitrogen was replaced by passing a nitrogen stream through the separable flask, and the temperature was raised to 60 ° C. Liquid temperature is 60
When the temperature reached ℃, 0.001 part of ferrous sulfate, 0.003 part of ethylenediaminetetraacetic acid disodium salt, and 0.24 part of Rongalit were dissolved in 10 parts of distilled water, and an aqueous solution was added to initiate radical polymerization. . The liquid temperature rose to 84 ° C. due to the polymerization of the butyl acrylate mixed liquid. This state was maintained for 1 hour to complete the polymerization of butyl acrylate to obtain a composite rubber latex. After the liquid temperature dropped to 75 ° C, a mixed liquid of 0.12 parts of tert-butyl hydroperoxide and 10 parts of methyl methacrylate was added to the composite rubber latex.
Drop over 25 minutes, then hold at 70 ° C for 4 hours,
The graft polymerization on the composite rubber was completed.

The obtained graft composite rubber latex was coagulated, separated, washed and dried in the same manner as in Reference Example 2 to obtain 95.5 parts of a dry powder of the graft composite rubber S-7. The number average particle diameter of this graft composite rubber is 0.03 μm, and it is 0.10 μm.
The volume fraction of particles larger than m was 2.1%.

Reference Example 9 Preparation of Polyorganosiloxane Rubber Latex SiLx-2: 2 parts of tetraethoxysilane, 0.5 part of γ-methacryloyloxypropyldimethoxymethylsilane and 97.5 parts of octamethylcyclotetrasiloxane were mixed to form a siloxane. 100 parts of mixture are obtained. Dodecylbenzene sulfonic acid 4 parts and dodecyl benzene sulfonic acid sodium 2
10 parts of the above-mentioned mixed siloxane in 200 parts of distilled water
Add 0 parts of the mixture, carry out preliminary dispersion with a homomixer and emulsification / dispersion with a homogenizer, heat at 80 ° C for 5 hours, then cool, let stand at 20 ° C for 48 hours, then adjust the pH to 7.0 with an aqueous sodium hydroxide solution. After the completion of the polymerization, the polymerization was completed to obtain a polyorganosiloxane latex SiLx-2. The polymerization rate of this polyorganosiloxane rubber was 89.6%, the average particle size was 0.05 μm, and the volume fraction of particles larger than 0.10 μm was 6
It was 7.3%.

Reference Example 10 Production of Grafted Composite Rubber S-8: Grafted composite rubber S-8 (97.1 parts) was prepared in the same manner as in Reference Example 2 except that the latex SiLx-2 obtained in Reference Example 9 was used.
Got The number average particle size of this graft composite rubber is 0.07μ
and the volume fraction of particles larger than 0.10 μm is 27.m.
It was 2%. Reference Example 11 Production of Grafted Composite Rubber S-9: Polyorganosiloxane rubber latex SiLx-3 was obtained in the same manner as in Reference Example 9 except that sodium dodecylbenzenesulfonate and dodecylbenzenesulfonic acid were changed to 0.67 parts. It was The obtained polyorganosiloxane rubber had a polymerization rate of 89.7% and a number average particle diameter of 0.16μ.
It was m.

33.4 parts of this latex SiLx-3 was sampled, placed in a separable flask equipped with a stirrer, 191.6 parts of distilled water was added, and after nitrogen substitution, the temperature was raised to 60 ° C. A mixed solution of 58.8 parts of acrylate, 1.2 parts of allyl methacrylate, and 0.3 part of tertiary butyl hydroperoxide was charged and stirred for 30 minutes, and the mixed solution was impregnated into polyorganosiloxane rubber particles. Next, 0.002 parts of ferrous sulfate, 0.006 parts of ethylenediaminetetraacetic acid disodium salt, Rongalit.
An aqueous solution prepared by dissolving 26 parts in 10 parts of distilled water was added to initiate radical polymerization, and then the internal temperature was maintained at 82 ° C. for 1 hour to complete the polymerization to obtain a composite rubber latex. Liquid temperature is 75
After the temperature was lowered to 0 ° C, a mixed solution of 0.12 parts of tert-butyl hydroperoxide and 30 parts of methyl methacrylate was added dropwise to this composite rubber latex over 25 minutes.
The temperature was maintained at 70 ° C for 4 hours to complete the graft polymerization on the composite rubber.

The obtained latex of the graft composite rubber was coagulated, separated, washed and dried in the same manner as in Reference Example 2 to obtain 95.4 parts of a dry powder of the graft composite rubber S-9. The number average particle diameter of this graft composite rubber is 0.25 μm and is 0.10 μm.
The volume fraction of particles larger than m was 93.4%.

Reference Example 12 Grafted acrylic rubber S-1
Preparation of 0: In a separable flask equipped with a stirrer, distilled water 215
Parts, 1.0 part of sodium dodecylbenzene sulfonate and then a mixed solution of 68.6 parts of butyl acrylate, 1.4 parts of allyl methacrylate, and 0.2 parts of tertiary butyl hydroperoxide were charged, and the separable flask was charged. Perform nitrogen replacement by passing a nitrogen stream through the
The temperature was raised to 0 ° C. When the liquid temperature reached 60 ° C, 0.001 part of ferrous sulfate, 0.003 part of ethylenediaminetetraacetic acid disodium salt, and 0.24 part of Rongalit were added to 1 part of distilled water.
An aqueous solution dissolved in 0 part was added to initiate radical polymerization. Liquid temperature is 8 due to polymerization of butyl acrylate mixture.
It rose to 4 ° C. This state was maintained for 1 hour to complete the polymerization of butyl acrylate to obtain an acrylic rubber latex. After the liquid temperature dropped to 75 ° C, te was added to this latex.
A mixture of 0.12 parts of rt-butyl hydroperoxide and 30 parts of methyl methacrylate was added dropwise over 25 minutes,
Then, the temperature was kept at 70 ° C. for 4 hours to complete the graft polymerization on the acrylic rubber. The obtained graft acrylic rubber latex was coagulated, separated, washed and dried in the same manner as in Reference Example 2 to obtain 96.5 parts of a dry powder of the graft acrylic rubber S-10. The number average particle diameter of this graft rubber was 0.31 μm, and the volume fraction of particles larger than 0.10 μm was 92.6%.

Reference Example 13 Production of Grafted Composite Rubber S-11: In Reference Example 1, the composition of the organosiloxane was changed to γ-
0.5 parts of methacryloyloxypropyldimethoxymethylsilane and 9 octamethylcyclotetrasiloxane
A non-crosslinked silicone latex SiLx- was prepared in the same manner as in Reference Example 1, except that the reaction product was made 9.5 parts and the cooled reaction product was immediately neutralized with an aqueous caustic soda solution without being kept at room temperature for 12 hours. Got four. The solid content of this latex was 17.
It was 9%. The number average particle size is 0.04μm, 0.10μ
The volume fraction of particles larger than m was 7.3%.

In Reference Example 2, latex SiLx-1 (5
Latex SiLx-4 (55.9 parts) instead of 4.9 parts)
A graft composite rubber S-11 (96.8 parts) was obtained in the same manner as in Reference Example 2 except that was used. The number average particle diameter of this graft composite rubber was 0.06 μm, and the volume fraction of particles larger than 0.10 μm was 6.3%.

Examples 1 to 5 Homotype polyacetal having MI of 18.2 g / 10 min or random copolymerization type polyacetal of 98 wt% trioxane and 2 wt% ethylene oxide of 8.2 g / 10 min of MI and Reference Example 2 Various resin compositions with the obtained graft composite rubber S-1 were prepared. These resin compositions 1
To each of the 00 parts, 0.5 part of carbon black (MCF-88 manufactured by Mitsubishi Kasei Co., Ltd.) was added and mixed, and the mixture was heated to a cylinder temperature of 200 ° C. in a twin-screw extruder (Werner Faudler Co. , ZSK-30 type)
The mixture was melt-kneaded and shaped into pellets. Each of the obtained pellets was dried and supplied to an injection molding machine (Promatt 165/75 type manufactured by Sumitomo Heavy Industries Ltd.), and injection molded at a cylinder temperature of 200 ° C and a mold temperature of 60 ° C to produce various test pieces. Obtained. Various physical properties were evaluated using these test pieces, and the results are shown in Table 2. It was found that the resin composition of the composite rubber-based graft copolymer and the polyacetal resin has excellent impact resistance and mechanical properties as shown in Examples 1 to 5.

When the L ^* value for colorimetry in the table is about 10, the pigment coloring property is judged to be good, and about 10 to 15 is a range having practical coloring performance. When the L ^* value is more than this, the coloring property becomes poor, and when it is 20 or more, it becomes unusable for practical use.

Examples 6 to 11 and Comparative Examples 1 to 4 20 parts of various graft rubbers and 80 parts of homotype polyacetal were mixed in the same manner as in Example 2 and shaped into pellets by a uniaxial extruder. Then, the pellets were dried, a test piece for measurement was manufactured by an injection molding machine, and Izod impact strength and flexural modulus were determined. The results are shown in Table 2.

From the results of Comparative Example 1, the rubber component was silicone.
It was found that the impact resistance of the graft copolymer of rubber alone decreased. Further, from the results of Examples 6 to 8, it was found that the ratio of the polyorganosiloxane to the polyalkyl (meth) acrylate in the composite rubber was better as the polyorganosiloxane content was smaller. Examples 9-1
From the result of 0, it was found that good impact resistance and mechanical strength were exhibited even when the amount of the vinyl-based monomer grafted to the composite rubber was changed. From the results of Example 11, it was found that even the graft composite rubber using the non-crosslinked polyorganosiloxane exhibited good impact resistance and mechanical strength.

However, as shown in Comparative Example 4, good impact resistance was not obtained with the acrylic rubber type (S-10). Further, according to Comparative Examples 2 and 3, the composite rubber-based graft copolymer having a number average particle size of 0.10 μm or more is 20
% (S-8, S-9), the impact resistance and mechanical strength were excellent, but the pigment colorability was poor.

[0065]

[Table 1]

[0066]

[Table 2]

[0067]

EFFECT OF THE INVENTION The resin composition of the present invention has extremely high impact resistance and excellent pigment colorability while maintaining the original excellent characteristics of the polyacetal resin.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichi Ito 20-1 Miyukicho, Otake City, Hiroshima Prefecture Mitsubishi Rayon Co., Ltd. Central Research Laboratory

Claims (2)

[Claims] 1. A composite rubber comprising a polyorganosiloxane component and an alkyl (meth) acrylate rubber component,
The number average particle size of the graft-polymerized one or more vinyl monomers is 0.01-0.07μm and is 0.10μ
A resin composition obtained by mixing a graft composite rubber (A) having a volume of particles larger than m of 20% or less of the total particle volume and a polyacetal resin (B). 2. The graft composite rubber (A) is 3 to 40% by weight.
2. The resin composition according to claim 1, wherein the polyacetal resin (B) is 97 to 60% by weight.