JPS5912694B2 - Method for producing glass fiber reinforced polyacetal resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a polyacetal resin composition reinforced with glass fibers, and more specifically, after covering chopped glass fiber strands with a vinyl thermoplastic resin, Part 5 relates to a method for producing a glass fiber reinforced polyacetal resin obtained by mixing it with a polyacetal resin.

Conventionally, the method of mixing glass fibers into resins to improve practical properties such as mechanical properties and thermal properties has been tried on many thermoplastic resins, including thermosetting resins, and has been used to impart excellent performance. It is well known that there are 10 possible compounds, and many patent applications have been published regarding their compositions or manufacturing methods, and products have been sold and put into practical use in the market.

However, when we actually examine the details in detail, we find that the behavior differs significantly depending on the type of resin. A method of reinforcing No. 15 polyacetal resin with glass fiber is proposed in Japanese Patent Publication No. 41-20831.

Molded articles with improved tensile modulus can be obtained from this composition, but impact resistance is not significantly improved and may even be reduced. In order to improve upon these drawbacks, as disclosed in Japanese Patent Publication No. 48-41261 and Japanese Patent Publication No. 49-1463, an inorganic filler material such as glass fiber is coated with polystyrene in advance and reinforced. A composition blended with a resin to be used has been proposed. However, when the glass fibers in these compositions are single fibers, they are easily damaged during molding even if their surfaces are coated with styrene resin. In addition, if the glass fiber is in the form of a strand made up of tens to hundreds of single fibers, it can be processed by the following method: (1) After passing it through an organic solvent solution of polystyrene, A method of volatilizing organic solvents.

(2) A method of contacting or spraying with an emulsion of polystyrene and then heating to remove water.

(3) A method of spraying a monomer onto the coating material and polymerizing it on the coating material by heating, leaving it to stand, or irradiating it.

Even if the glass fiber strand is coated with resin, the surface of each single fiber constituting the glass fiber strand cannot be coated with the resin.

During injection molding or extrusion molding, shearing forces act on the strands, and the strands are released into single fibers and are separated or broken, leading to a reduction in glass fiber addition efficiency. In view of this situation, the present inventors conducted various studies in order to achieve better glass fiber addition efficiency and to make the surface of the resulting molded product smooth. When coated with a polymer and dry blended with a polyacetal resin, the molded product obtained from this dry blend has a superior appearance and superior physical properties compared to molded products obtained from conventional compositions. Based on this discovery, he completed the invention of heather.

An object of the present invention is to provide a method for producing a glass fiber-reinforced polyacetal resin composition that has excellent physical properties such as impact resistance, appearance, etc., and has a high glass fiber addition efficiency. is a glass fiber chopped strand obtained by suspension polymerizing one vinyl compound monomer or a mixture of two or more vinyl compound monomers that are copolymerizable with each other in the presence of a glass fiber chopped strand. A method for producing a glass fiber-reinforced polyacetal resin composition comprising dry blending 5-50% by weight of glass fiber-containing polymer pellets containing 20-90% by weight and 95-50% by weight of polyacetal resin pellets. Exists.

Hereinafter, to explain the present invention in detail, vinyl compound monomers referred to in the present invention include monovinyl aromatic compounds such as vinylristyrene chloride, α-methylstyrene, vinyltoluene, and chlorostyrene; acrylonitrile, methacrylonitrile; and other vinyl cyanide compounds; other examples include acrylic acids, methacrylic acids, acrylic esters, and methacrylic esters.

These monomers can be used alone, but they can also be used in combination of two or more types that can be copolymerized with each other. When used as a combination of two or more types, a combination of a monovinyl aromatic compound and a vinyl cyanide compound is preferred.
The chopped glass fiber strand according to the present invention is preferably made by bundling tens to hundreds of single fibers with a diameter of 20μ or less, and has a length of 2 to 101! This is a chopped strand that has been cut into approximately 1.

If the length of the chopped glass fiber strands is outside the range of 2 to 10 nm, the glass fiber-containing polymer will become too short or too long, resulting in irregular sizes with the pellets, and the polyacetal to be reinforced. When blended into resin pellets, it is not preferable because it is not uniformly dispersed in the blend. The glass fiber-containing polymer according to the present invention can be produced by suspension polymerization of the monomers by coexisting one or more of the monomers with the chopped glass fiber strands in a suspension polymerization system. can get.

The glass fibers used in this case are commercially available chopped strands that are soaked in the monomer used for polymerization in advance to make them wet. This is preferable because it is completely coated with the polymer. The amount of glass fiber chopped strands to be present in the polymerization system during polymerization can be from 5 to 1000 parts by weight per 100 parts by weight of the monomer, and among them, the ratio of monomer to glass fiber is 10
A range of 0:50 to 500 is particularly preferred. During suspension polymerization, the ratio of aqueous medium to monomer is 100% monomer.
100 to 3000 parts by weight of the aqueous medium is suitable. If less than 100 parts by weight of aqueous medium are used per 100 parts by weight of monomer, as the polymerization proceeds,
The overall mixture of monomer and polymer becomes extremely viscous, making it difficult to stir the resulting mixture, as well as making heat transfer or solubility control difficult, thus making glass fiber-containing polymers of uniform properties. This is undesirable as it may cause disadvantages such as not being able to obtain the desired benefits. If the amount of the aqueous medium is 3000 parts by weight or more, the amount of monomer charged is inevitably limited and productivity is reduced, which is uneconomical. The polymerization is carried out by the suspension polymerization method as described above, and the suspension stabilizers that can be used at this time are preferably those used when the vinyl compound monomer is polymerized by the suspension polymerization method, such as Various saponified products of polyvinyl acetate (polyvinylalcono(c), styrene)
Examples include water-soluble polymer compounds such as maleic acid copolymer, polysodium methacrylate, and copolymer of 2-ethylhexyl acrylate and acrylic acid, and these can be used alone or in combination of two or more.

Furthermore, these suspending agents and certain surfactants can also be used in combination. Furthermore, inorganic compounds such as calcium carbonate can also be used. For such a suspension polymerization reaction, a vertical reactor commonly used for suspension polymerization can be used without particular restrictions. In addition, when polymerizing the vinyl compound monomer, it is preferable to use a polymerization initiator, and as such a polymerization initiator, a commonly used oil-soluble radical-generating polymerization initiator is preferable, and the amount used is varies depending on the nature of the polymerization initiator and the depth of polymerization, but
0.005 to 3 per 100 parts by weight of monomer.

It can be used in a proportion of 0 parts by weight.

Surprisingly, the glass fiber-containing polymer obtained by the above method has a surface coated with a polymer in which a large number of chopped strands are arranged and aggregated in a certain direction, and its appearance resembles that of extruded strands. It has a similar form to pellets produced in a machine.

Note that when suspension polymerization is carried out using the above method, a polymer powder that does not contain glass fibers may be produced as a by-product along with the glass fiber-containing polymer. use. This glass fiber-containing polymer has 30 to 9 chopped glass fiber strands.
The content is preferably 0% by weight, preferably 40 to 85% by weight.

And its average diameter is about 1~8 strokes, and its average length is about 2~
10 pieces are preferred. Anything outside the above range,
If the particle size is too large or too small, there will be a difference in the size of the base polyacetal resin pellets, and when the two are dry blended, the glass fiber-containing polymer will not be dispersed uniformly. So I don't like it. In the method of the present invention, a polyacetal resin is blended into the glass fiber-containing polymer produced by the above method.

The polyacetal resin in the present invention refers to polymers produced by various methods by polymerizing formaldehyde, trioxane, or higher aldehydes, and copolymers containing oxymethylene groups.

The mixing ratio of the glass fiber-containing polymer and the polyacetal resin is in the range of 5 to 50% by weight for the former and 95 to 50% by weight for the latter. If the glass fiber-containing polymer is less than 5% by weight, the amount of glass fiber in the final composition will be too small, and the purpose of improving and improving various properties by adding glass fiber will not be achieved, which is not preferable. Conversely, 50% by weight
Above this, the glass fiber addition efficiency is not improved and becomes meaningless. A particularly preferred range is 20 to 45% by weight of the former. In the method of the present invention, a glass fiber-containing polymer exhibiting a pellet-like appearance may be blended with polyacetal resin pellets or granules.

Blending of the two can be easily done using various conventional mixers. The dry blended product can be subjected to injection molding, extrusion molding, etc. in the form of a dry blend. The step of kneading the blend in an extruder to form glass fiber-containing pellets can be omitted.

In addition, in the resin composition according to the method of the present invention, the surface of the chopped glass fiber strand is coated with a polymer, and the surface of each single fiber constituting the strand is also coated, and the glass fibers are bonded between each other. Because it is firmly attached,
The glass fibers are difficult to break during molding, and the microfibers that make up the strands are also difficult to separate. Therefore, a product with improved glass fiber addition efficiency can be obtained. Furthermore, there is less direct friction between the glass fibers and the molding machine, and damage caused by the glass fibers to the molding machine can be reduced.
Its industrial utility value is extremely large. Example 1 Using a vertical autoclave with a capacity of 31 equipped with a reflux condenser, a depth meter, an anchor-type stirrer, and a buffer, the autoclave was first charged, the pressure inside the autoclave was reduced, nitrogen gas was introduced, and the glass fibers were replaced with nitrogen. The chopped strands were left immersed in the monomer mixture for 10 minutes.

Next, an aqueous solution consisting of this autoclave was charged, and the internal temperature was raised to 80° C. while stirring, and the polymerization reaction was continued at this temperature for 5 hours. After this, unreacted monomers were removed by stripping. The conversion rate of monomer to polymer is 92
It was %. After the polymerization was completed, water and polymer were separated from the slurry using gauze, and what remained on the gauze was washed with water and dried.

The product is about 249g of a glass fiber-containing polymer with a pellet-like appearance of about 3mm long and 2~31u in diameter, and about 90f of polymer powder that does not contain glass fiber! It was hot. The glass fiber content of the glass fiber-containing polymer was approximately 82% by weight.
When the cross section of this product was observed, it was found that a plurality of chopped glass fiber strands were bundled together and coated with a polymer. The polymer coating the chopped glass fiber strands has a styrene to acrylonitrile ratio of approximately 8.
The specific viscosity was 0.071 when 0.1 gr of the polymer was dissolved in 100 d of dimethylformamide and measured at 25°C. Only the glass fiber-containing polymer obtained by the above method was taken out, and this product had a concentration of 26% by weight.
and 74% by weight of polyacetal resin (manufactured by Asahi Kasei Corporation: Tenatsuku 5010), and the glass fiber content in the final resin composition was 21.3%.
A dry blend product of % by weight was obtained. Test pieces were prepared from this dry blend product by injection molding and various properties were measured.

These results are shown in Table 1. The mechanical properties were measured according to the following method. The same applies to the following examples. Comparative Example 1 79% by weight of polyacetal resin (Tenac 5010) was blended with 21% by weight of the same glass fiber chopped strands used in Example 1, and melt-kneaded using an extruder to form pellets.

Test pieces were prepared from the pellets in the same manner as in Example 1, and various properties were measured. The results are shown in Table 1. Example 2 31% by weight of the glass fiber-containing polymer obtained by the method described in Example 1 and 69% by weight of polyacetal resin (Dyuracon M9O-02, manufactured by Polyplastics Co., Ltd.) were dry blended, and the final A dry blend product was obtained in which the glass fiber content in the resin composition was 25.4% by weight.

Test pieces were prepared from this dry blend product in the same manner as in Example 1, and various properties were measured.

The results are shown in Table 1. Comparative Example 2 Commercially available glass fiber reinforced polyacetal resin (manufactured by Polyplastics Co., Ltd.: Jyuracon GC-25).

Glass fiber content: 25.8% by weight), test pieces were prepared in the same manner as in the examples, and various properties were measured. The results are shown in Table 1. In the composition obtained by the method of the present invention, not only the surface of the chopped glass fiber strand but also each single fiber constituting the strand is coated with a polymer. There's not much to do.

Claims (1)

[Claims] 1 Glass fiber chopped strands obtained by suspension polymerizing one vinyl compound monomer or a mixture of two or more vinyl compound monomers copolymerizable with each other in the presence of glass fiber chopped strands. 5 to 50% by weight of glass fiber-containing polymer pellets containing 5% to 50% by weight;
A method for producing a glass fiber-reinforced polyacetal resin composition, which comprises dry blending 95 to 50% by weight of polyacetal resin pellets.