JPS5915948B2 - polyamide composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polyamide composition having excellent water resistance and solvent resistance.

More specifically, the present invention relates to a polyamide composition having excellent water resistance and solvent resistance, which is composed of polyamide and 0.5 to 3.0 parts by weight of polyoxymethylene based on 100 parts by weight of the polyamide. Polyamide is useful as a hot-melt adhesive because it has excellent adhesion, high cohesive strength, and excellent impact resistance to fibers, molding materials, various films, sheets, etc., as well as metals, glass, and wood. And
Most of them are commercialized as adhesive molded products in the form of films or sheets.

However, polyamides with low melting points have poor water resistance and solvent resistance.For example, even if adherends are bonded with low melting point polyamides, the wet dimensional stability of the bonded part may not be excellent, or the solvent atmosphere may It is unsuitable as an adhesive for bonding materials that can be used underneath, as the adhesive strength or impact resistance is extremely reduced.

In order to eliminate these drawbacks, it has been known to mix epoxy resins, phenol resins, melamine resins, etc. with low melting point polyamides. but,
Since these resins are thermosetting resins, polyamides blended with these resins have the disadvantage that they cannot be melt-molded, which is a general molding method for polyamides.

As a result of intensive research, the present inventors aimed to obtain a low-melting polyamide with excellent water resistance and solvent resistance that can be melt-molded.
It was discovered that by adding hydrophobic polyoxymethylene to the polyamide, the water resistance and solvent resistance of the polyamide 5 were improved without impairing the adhesive strength and impact resistance, and the present invention was completed. I reached it.

The polyamide composition of the present invention comprises polyamide and 0.5 to 3.00 parts by weight of polyoxymethylene based on 100 parts by weight of the polyamide.

Polyamide has a melting point of 20 in terms of adhesiveness and impact resistance.
Preferably, the temperature is 0°C or lower. Examples of the low melting point polyamide having a melting point of 200°C or lower include nylon-11, nylon-12, and copolymerized polyamide.
The copolyamides are synthetic copolyamides whose main chain consists of amide bonds, such as ε-caprolactam, ω-lau-lactam, aminoundecanoic acid, hexamethylene diammonium adipate, hexamethylene diammonium sebacate, and hexamethylene diammonium sebacate. Examples include copolyamides comprising at least two types of polyamide-forming monomers such as methylene diammonium dodecanate and hexamethylene diammonium terephthalate.

As a copolymerized polyamide component, among the above polyamide-forming monomers, such as ω-laurolactam, aminoundecanoic acid, and hexamethylene diammonium dodecanate,
A copolyamide containing at least one type of group containing a large number of paraffin groups such as bemethylene groups in the group forming an amide bond has a low melting point and high adhesive strength, and is therefore suitable as a material for hot melt adhesives. .

In the present invention, polyoxymethylene refers to general formula 1 (C
It is a polymer consisting of repeating units of H2O+n (where n indicates the degree of polymerization), and has a molecular weight of 5000 to 200,00.
A commonly used polymer having a degree of polymerization of 0 is used.

The polyoxymethylene polymer may be produced by any known method.

Specific examples include the following. Formaldehyde monomer, trioxane or tetraoxane, cyclic ethers such as ethylene oxide and propylene oxide, cyclic formals such as 1,3-dioxolane, 1,4-butanediol formal, diethylene glycol formal, vinyl monomers such as styrene, methyl vinyl ether, benzyl vinyl ether, Cationic copolymerization is performed with olefins such as isobutyne, and the resulting crude copolymer is heated in vacuum, under nitrogen, or with ammonia,
The ends of the copolymer or crude copolymer from which thermally unstable parts have been removed by heat treatment in a solvent such as water, alcohol, or hydrocarbon containing an alkaline substance such as amine, caustic soda, or sodium acetate are treated with acetic anhydride. esterify or
These include copolymers etherified with orthoformic acid esters and acetals.

Furthermore, it may be esterified with a hydroxyl group or carboxylic acid at the terminal of the polymer molecule, or may be protected by other methods. The appropriate amount of polyoxymethylene to be blended into the copolyamide is 0.5 to 3.0 parts by weight based on 100 parts by weight of the polyamide.

If the blending amount is 0.5 parts by weight or less, no improvement in water resistance and solvent resistance of the resulting copolyamide is observed. Moreover, if it exceeds 3.0 parts by weight, the adhesive strength or impact resistance of the resulting copolyamide will decrease, which is not preferable. In the present invention, polyamide and polyoxymethylene can be mixed by a method of melt mixing, a method of mixing both as a solution and removing the solvent, a method of adding and dissolving polyoxymethylene in a solution of polyamide, and mixing both. Examples include a method of mixing polyamide film or chips as a powder, and a method of bringing a polyamide film or chip into contact with a polyoxymethylene solution or powder, and then heat-processing the film or chip.

Among these, the polyamide composition obtained by the melt-mixing method provides the best results in terms of improved water resistance and solvent resistance. In the present invention, the mixing temperature when melt-mixing the copolyamide and polyoxymethylene is appropriately selected within a temperature range in which the copolyamide and polyacetal melt and do not substantially decompose.

When used alone, polyacetal tends to undergo thermal decomposition, but when polyamide is present in the coexistence, there is almost no change. Therefore,
When melt-mixing polyamide and polyacetal, first mix both at room temperature and then melt-mix.
Alternatively, it is preferable to add polyacetal to the molten polyamide. As the melt-mixing device, equipment such as an autoclave or a single-screw extruder can be used.

In particular, if a single-screw extruder is used, the water-resistant and weld-resistant polyamide produced by melt-mixing and melt-mixing copolymerized polyamide and polyacetal can be processed into a film or sheet at the same time, increasing productivity. It will be extremely advantageous. The polyamide composition of the present invention has excellent stability in solvents such as water, methanol, ethanol, butanol, and phenol compared to conventional polyamides,
It can be used as an adhesive for various polymer materials, metals, glass, wood, etc. due to its excellent adhesion properties, and as an improved molding material in a steam atmosphere or in various solvents, it has no adhesive strength, impact resistance, etc. Since it does not deteriorate the properties of polyamide, it can be used in a wide range of fields.

The present invention will be specifically explained below with reference to Examples. Example 1 35 parts by weight of purified ε-caprolactam, 40 parts by weight of hexamethylene diammonium adipate, 25 parts by weight of ω-laurolactam, 40 parts by weight of water, 50 parts by weight
1 After charging into an autoclave and purging with nitrogen gas, 2
The temperature was raised to 280C over a period of time.

Next, while stirring, the temperature was maintained at the same temperature for 3 hours under an increased pressure of 15k9/~, and then the pressure was released to 1 hour to normal pressure, nitrogen was further applied, and the temperature was maintained for 3 hours. A copolyamide was obtained as transparent chips with a melting point of 150° C. and ηr=2.25 (relative viscosity in 98% sulfuric acid).

The chips were dried with a 1501 dryer, and then the dried chips and polyoxymethylene with a molecular weight of 20,000 were mixed in the proportions shown in Table 1, and the mixture was fed to a 30 mm diameter extruder at a mixing temperature of 220°C. The mixture was melt-mixed, extruded as it was from a spinneret, and spun.

The obtained undrawn yarn was drawn at a drawing ratio of 3.2 to obtain a drawn yarn of 70 denier and 24 filaments. Next, the drawn yarn was cut to a length of 20 CTIL, one end was fixed to a fixed shaft, a load of 29 was applied to the other end, and the drawn yarn was suspended.
The length (LCTIL) of the drawn yarn when a load was applied was measured, and then, as shown in FIG. 1, it was left in saturated steam for one week at room temperature. After that, the drawn yarn was taken out and the length (L'01rL) of the drawn yarn after being left was measured. The results are shown in Table 1. As shown in Table 1, by melt-mixing polyoxymethylene and copolyamide,
Compared to copolyamide alone, it has extremely good dimensional stability against water vapor. Example 2 Copolyamide obtained by polymerization in Example 1. and polyoxymethylene in the proportions shown in Table 2, 30ml/L
The mixture was supplied to a φ extruder, melted and fused at a mixing temperature of 220° C., and then formed into a film using a slit spinneret (slit width: 80 mm) to obtain a film with a thickness of 60 μm.

Aluminum plate whose surface was cleaned with trichlorethylene (
25 x 100 x 0.2 m711) as the adherend,
The film obtained above was sandwiched between the adherends and heated to 200°C.
After hot pressing at a pressure of 4 kg/d for 5 minutes, the product was rapidly cooled to room temperature.

The adhesive adherends were then treated in the solvents and conditions shown in Table 2, removed from the solvent after treatment, and immediately measured for tensile shear strength.

The tensile shear strength was measured by Schottspa type 1 tensile strength test. The measurement temperature was room temperature, and the tensile speed was 10 mm/Mi.
It is n. The results are shown in Table 2. Adhesives containing 0.3 to 3.0 parts by weight of polyoxymethylene have almost no difference in tensile shear strength and peel strength after each solvent treatment, and have good water resistance and solvent resistance. It is clear that he is good at it.

If the weight is less than 0.3, the decrease due to processing is significant,
Moreover, if it exceeds 3.0 parts by weight, the adhesive strength of the adhesive itself decreases, which is not preferable.

It can be seen that the copolyamide in which polyoxymethylene is melt-mixed shows no decrease in tensile shear strength even after each solvent treatment, and has good solvent resistance.

When the amount of polyoxymethylene is 0.3 parts by weight or more, the effect of solvent resistance is significantly lost. If the amount exceeds 3 parts by weight, the tensile shear strength of the copolyamide itself before solvent treatment decreases, making it undesirable as an adhesive material.

Comparative Example 2 parts of polyoxyethylene glycol having an average molecular weight of 6000 was blended with 100 parts by weight of the copolyamide obtained by polymerization in Example 1, and the mixture was fed to a 30 Cφ extruder and the mixture was heated to a mixing temperature of 220°C. The mixture was then melt-mixed using a slit spinneret (slit width: 80 TLTfL) to form a film with a thickness of 60 μm.

Aluminum plate whose surface was cleaned with trichlorethylene (
25 x 100 x 0.2 mm) was used as an adherend, and the film obtained above was sandwiched between the adherends and hot pressed at a temperature of 200°C and a pressure of 4 kg/CT7L for 5 minutes, and then rapidly cooled to room temperature.

Next, the adhesive adherends were treated with the solvent and under the conditions shown in Table 3, and after the treatment, they were taken out of the solvent and the adhesive strength was immediately measured under the same conditions as in Example 2.

The results are shown in Table 3. As can be seen from Table 3, water resistance and solvent resistance after adhesion could not be expected by melt-mixing polyoxyethylene glycol.

[Brief explanation of the drawing]

FIG. 1 shows an apparatus for measuring the dimensional stability of copolyamide drawn yarn against water vapor. In the figure, A is a glass plate, B is a cylindrical glass container, and C
is a column, D is a fixed shaft, E is a weight of 29, F is a drawn copolyamide yarn, and G is water placed to make the inside of the container saturated steam.

Claims (1)

[Claims] 1 Polyamide with a melting point of 200°C or less and the polyamide 10
A polyamide hot-melt adhesive composition comprising 0.5 to 3 parts by weight of hydrophobic polyoxymethylene.