JPH0627204B2 - Polyoxymethylene reinforcing fiber - Google Patents

Description

TECHNICAL FIELD The present invention relates to a thermoplastic resin reinforcing fiber.

(Prior Art) Polyoxymethylene (POM) has excellent tensile strength, fatigue resistance, hygroscopicity, and weather resistance and is widely used in machine parts, automobile parts, and the like.

In order to increase the strength of POM products, isocyanate is mixed in POM and reinforcing fibers such as glass fibers are further mixed.

(Problems to be Solved by the Invention) The related art has the following problems.

In order to obtain a POM product having extremely high strength, 0.1-5 wt% of isocyanate and 5-60w of POM are used.
It is necessary to add t% reinforcing fiber and mix the three uniformly under heating.

Mixing the three in each case not only complicates the process but also makes it difficult to mix uniformly because the amount of isocyanate with respect to POM is relatively small, and variations in quality are likely to occur.

Further, it is necessary to use about 0.1 to 5 wt% of isocyanate with respect to POM.

The present inventor, by performing various treatments on the glass fiber,
Attempts have been made to improve the strength of POM products and solve the above-mentioned problems without using isocyanate.

Although it was possible to improve the strength of the POM product as shown in Comparative Example 3 by using the glass fiber treated with the acrylic resin, the obtained POM product was poor in thermal stability and contacted with hot water. However, there is a problem in that the strength is significantly reduced when used as such, and good results could not be obtained by this method.

Further, as shown in Comparative Example 2, by using the epoxy resin, the stability of the POM product could be improved to some extent, but the tensile strength, the tensile strength after the hot water test and the IZOD impact strength were almost improved. No good results could be obtained in this case either.

The present inventor has further attempted to solve the above-mentioned problems by attaching an isocyanate to a reinforcing fiber. However, since the isocyanate easily reacts with water, it is quickly decomposed before being mixed with POM, and the purpose is I could not achieve it.

The present invention solves the above-mentioned problems, does not require mixing of isocyanate each time when molding POM, has sufficient strength, and has good heat resistance and hot water resistance,
It is an object of the present invention to provide a POM-reinforcing fiber so that a homogeneous POM can be obtained.

(Means for Solving the Problem) In order to achieve the above object, in the present invention, a glass fiber having a blocked polyisocyanate attached thereto is used as the POM reinforcing fiber.

Next, the present invention will be described more specifically.

As a POM, especially a POM with a degree of polymerization of 10,000 to 100,000
Is suitable.

Examples of blocked polyisocyanates include RNCO
A compound having the general formula R-NH-C-B in which the isocyanate represented by is blocked with B is used.

As the RNCO, a polyisocyanate such as TDI, MDI, HDI, or an isocyanate prepolymer can be used.

As B, phenols, alcohols, oximes,
Examples thereof include sodium bisulfite, but those having a dissociation temperature at the time of use of 200 ° C. or lower are suitable.

In the present invention, the glass fiber to which the blocked isocyanate described above is attached (the present glass fiber) is used and mixed with POM under heating. The amount of blocked isocyanate adhering to the glass fiber is 0.1 to 10 wt%,
Desirably, the amount is 0.5 to 3 wt%.

If the attached amount of blocked isocyanate is too small, the effect of improving the physical properties of the POM product is not sufficient, and even if the attached amount is too large, the above effect does not improve so much, but rather there are drawbacks such as hue deterioration and cost increase. It is easy to occur.

The glass fiber has a diameter of 3 to 23 μ, preferably a diameter of 5
The one having a size of ˜16 μ is suitable.

In addition, the glass fiber is a strand bundled with a sizing agent,
It is preferably used in the form of chopped strands (CS) cut to a length of 1.5 to 50 mm, preferably 3 to 6 mm, particularly 0.001 to 0.2 wt% of a coupling agent, preferably a silane coupling agent, preferably 0.01 to 0.1wt%,
A film forming agent such as urethane containing 0.1 to 1.0 wt%, preferably 0.3 to 0.8 wt% is suitable.

The method for applying the blocked isocyanate is not particularly limited, and the glass fiber may be bundled by using a sizing agent containing the blocked isocyanate, or the blocked isocyanate may be attached to the bundled glass fiber. it can.

A film forming agent is contained in the sizing agent in order to prevent fluffing, yarn breakage, and the like during the yarn collecting and to improve the yarn collecting operation. As the film-forming agent, urethane, epoxy resin, acrylic resin, etc. are used, and these are selected depending on the use of the glass fiber bundle obtained by threading, etc.
In any case, in order to improve the workability of yarn collecting, it is necessary to include a certain amount or more of the film forming agent in the sizing agent. This required amount depends on the type of film forming agent.

The method for mixing the glass fiber and the POM resin is not particularly limited, and a conventional method can be preferably used.

For example, the present glass fiber and POM may be mixed under heating to obtain a POM product by an injection molding method, or the above mixture may be once pelletized, and then the pellet may be used to produce a PO
It can also be an M product or an intermediate.

(Function) By using the glass fiber to which the blocked isocyanate is attached for POM reinforcement, the blocked isocyanate is dissociated by the heating at this time to generate the isocyanate on the glass fiber surface.

The produced isocyanate reacts with POM at the interface between the glass fiber and POM and improves the physical properties of the POM product.

Further, the blocked isocyanate is adhered to the glass fiber, and the dissociation of the glass fiber produces the isocyanate, thereby preventing the variation in quality and the increase in time and labor required when the isocyanate is mixed with POM.

Further, by dissociating the blocked isocyanate on the surface of the glass fiber to form the isocyanate on the surface of the glass fiber, the amount of the isocyanate is changed to that of the glass fiber and PO.
It is especially large near the interface of M, and P
Improve the physical properties of OM products.

Example 1 1.0 wt% of isocyanate blocked with methylethylketoxime and 0.0% of aminosilane (upling agent)
A glass fiber bundle obtained by binding 2,000 glass fibers having a diameter of 10 μ and having 2 wt% and 0.3 wt% of urethane (film forming agent) attached thereto was cut into a CS having a length of 3 mm.

25 parts by weight of CS and 75 parts by weight of POM were mixed at 200 ° C., and an ASTM II test piece was manufactured by an injection molding method.

Using this test piece, the physical properties measured by the methods of ASTM D638, D790, and D256, heat resistance, and tensile strength after immersion in hot water of 100 ° C. for 75 hours are shown in the attached table.

In the heat qualitative column of the attached table, ◎ is extremely good, ○ is good, ×
Indicates a defect.

(Example 2) The result of performing the same experiment as in Example 1 except that the isocyanate of Example 1 was replaced by an isocyanate blocked with sodium bisulfite is shown in a separate table.

(Comparative Examples 1, 2, 3) Instead of the glass fiber of Example 1, 0.2 wt% of aminosilane was used.
%, Urethane 1.0 wt%, epoxy resin 1.0
The results of an experiment similar to that of the example using the glass fiber coated with wt% of acrylic resin and 0.5 wt% of acrylic resin are shown in a separate table. Incidentally, in these comparative examples urethane, epoxy resin,
The reason why the amount of the acrylic resin (film forming agent) is different from that of the examples is that the same yarn-collecting property as that of the examples is obtained.

(Comparative Example 4) Instead of the CS of Example 1, the CS of Comparative Example 1 was used, and 5 parts by weight of isocyanate (MDI) was used, and the same experiment as in the case of parts by weight 1 was conducted.

The amount of this isocyanate used was about 20 times that in Example 1.

Comparative Example 5 The results of the same experiment as in Comparative Example 4 except that the amount of isocyanate used in Comparative Example 5 was the same as in Example 1 are shown in the attached table.

(Effects of the Invention) Products such as POM having small variations in quality and excellent physical properties can be obtained.

Eliminates the need for mixing and reduces the amount of isocyanate used.

Claims (2)

[Claims] 1. A polyoxymethylene reinforcing fiber having a blocked isocyanate attached thereto. 2. The polyoxymethylene reinforcing fiber according to claim 1, wherein the adhesion amount of the blocked isocyanate is 0.1 to 10 wt% of the weight of the fiber.