JPH0339109B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a resin composition containing polyalkylene terephthalate resin as a main component and having excellent impact resistance, cold resistance, and weather resistance. More specifically, the present invention relates to a resin composition obtained by blending a specific acrylic graft copolymer with a polyalkylene terephthalate resin. Polyalkylene terephthalate resins, especially polybutylene terephthalate and polyethylene terephthalate, have excellent heat resistance, weather resistance, and chemical resistance, and are therefore used for various purposes. However, a serious drawback of this polyalkylene terephthalate resin is low impact resistance, especially notched impact resistance, and various proposals have been made to improve this. For example, Japanese Patent Publication No. 51-25261 and Japanese Unexamined Patent Publication No. 51-25261 disclose a method in which a graft copolymer mainly composed of diene rubber is mixed with a polyalkylene terephthalate resin.
Publication No. 57-94038 etc. have been proposed. However, because diene rubber contains many double bonds in its main chain, it deteriorates when exposed to ultraviolet rays, and when used outdoors for a long time, it has the drawback of easily causing rough appearance and a decrease in impact resistance. Further, as a mixture of an acrylic rubber graft copolymer and a polyalkylene terephthalate resin, JP-A-52-150466 and JP-A-54-31456 disclose
There are proposals such as Japanese Patent Application Laid-Open No. 57-94037. The present inventors have developed a variety of methods to maintain the excellent heat resistance and chemical resistance of polyalkylene terephthalate resin while imparting high impact resistance, especially cold resistance, and weather resistance required for automobiles, electrical parts, etc. After conducting a study, it became clear that although various proposals have been made in the past, nothing satisfactory has yet been achieved. In view of the current situation, we have conducted intensive studies to improve the impact resistance, especially the cold resistance, of polyalkylene terephthalate resins, and to develop resin compositions that also have weather resistance. As a result, regarding the acrylic rubber-based graft copolymer blended with polyalkylene terephthalate resin, when adding a crosslinking agent to the acrylic acid alkyl ester elastomer and graft polymerizing it, (1) a large amount of (2) Sufficient graft cross-linking cannot be obtained with the amount of cross-linking agent within the range that provides appropriate rubber elasticity; It was discovered that the compatibility with polyalkylene terephthalate resin deteriorates and high impact strength cannot be obtained. In order to overcome such problems, the present inventors
In the step, a polymer having sufficient rubber elasticity is formed with an acrylic acid alkyl ester and a small amount of a crosslinking agent,
In the second step, by polymerizing a large amount of a mixture consisting of a polyfunctional grafting agent and an acrylic acid alkyl ester, while maintaining sufficient rubber elasticity,
By forming an acrylic acid alkyl ester elastic body with a two-layer structure that facilitates subsequent graft cross-linking, and blending the graft copolymer and polyalkylene terephthalate resin into this elastic body, high impact strength is achieved. It has been discovered that a composition exhibiting the above properties and having good weather resistance can be obtained, and the present invention has been achieved. That is, the present invention uses an acrylic acid alkyl ester having an alkyl group having 2 to 10 carbon atoms, and in the first step, the acrylic acid alkyl ester is
30 to 70 parts by weight of a mixture consisting of 99.9 to 97% by weight and 0.1 to 3% by weight of a crosslinking agent is emulsion polymerized, and in the second step, 99 to 97% by weight of acrylic acid alkyl ester and 1
An acrylic elastomer (A) is formed by polymerizing 70 to 30 parts by weight of a mixture consisting of 1 to 3% by weight of a polyfunctional graft cross-agent having 1 to 3 allyl groups, and 100 parts by weight of this elastomer (A). methacrylic acid alkyl ester
25 to 125 parts by weight of a monomer or monomer mixture consisting of 100 to 60% by weight, 40 to 0% by weight of an aromatic vinyl compound, and 20 to 0% by weight of a vinyl cyanide compound,
A resin composition with excellent impact resistance, cold resistance, and weather resistance, consisting of 3 to 45 parts by weight of a graft copolymer (B) obtained by stage or multistage graft polymerization and 97 to 55 parts by weight of a polyalkylene terephthalate resin. It is. The first and second stage acrylic acid alkyl esters constituting the acrylic elastomer (A), which is the base polymer of the graft copolymer (B) used in the present invention, have a carbon atom number in the alkyl group. 2 to 10 acrylic acid alkyl esters, such as ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, hexyl acrylate, n-octyl acrylate, and 2-ethylhexyl acrylate. is used. These monomers may be used alone or in combination, and of course different acrylic acid alkyl esters may be used in the first stage and the second stage. The crosslinking agent used in the first step includes divinylbenzene, diacrylic acid ester or dimethacrylic acid ester which is an ester of acrylic acid or methacrylic acid and a polyhydric alcohol, or a crosslinking agent having an allyl group, such as triallyl cyanurate, isocyanurate. Triallyl acid, allyl methacrylate, allyl grafting acid, diallyl itaconate, diallyl phthalate, and the like can be used.
In the first stage, acrylic acid alkyl ester
30 to 70 parts by weight of a mixture consisting of 99.9 to 97% by weight and 0.1 to 3% by weight of a crosslinking agent is emulsion polymerized. At this time, if the amount of crosslinking agent is less than 0.1% by weight, the crosslinking density is low; If the amount exceeds %, the elastic properties will be lost. In particular, a range of 0.1 to 0.8% by weight is desirable because it exhibits ideal rubber elasticity. The graft crosslinking agent used in the second step is a graft crosslinking polyfunctional crosslinking agent having one or more allyl groups in the molecule, such as triallyl cyanurate, triallyl isocyanurate, allyl methacrylate, allyl acrylate, and itacon. acid diallyl,
Diallyl phthalate and the like can be used. Second
At the stage, acrylic acid alkyl ester 99~
70 to 30 parts by weight of a mixture consisting of 97% by weight and 1 to 3% by weight of the above-mentioned graft cross-agent is emulsion polymerized. At this time, if a graft cross-agent that does not have an allyl group is used, sufficient graft cross-reaction can occur. cannot be expected. Furthermore, if the amount of the graft cross-agent is less than 1% by weight, sufficient graft cross-linking will not be obtained and the compatibility with the polyalkylene terephthalate resin will deteriorate. Also, if the amount exceeds 3% by weight, the elastic properties of the second stage portion will be too impaired and impact resistance will be lost. In producing the acrylic elastomer (A), ordinary anionic, cationic, and nonionic surfactants can be used as emulsifiers.
Furthermore, depending on the type of emulsifier used, when the pH of the polymerization system becomes alkaline, an appropriate pH regulator may be used to prevent hydrolysis of the acrylic acid alkyl ester. As the polymerization initiator, common water-soluble inorganic initiators such as persulfates can be used alone, or in combination with sulfites, bisulfites, thiosulfates, etc., as redox initiators. Furthermore, redox initiators such as organic hydroperoxide-ferrous salts, organic hydroperoxide-sodium formaldehyde sulfoxylate, or azo compounds can also be used. Polymerization can be carried out at a temperature above the decomposition temperature of the initiator and under conventional emulsion polymerization conditions. Both the first and second stage polymerizations can be carried out by adding the entire amount of each monomer mixture at once, or while continuously adding the entire amount or a portion thereof. However, from the viewpoint of stability of polymerization, removal of heat of polymerization reaction, etc., it is preferable to carry out polymerization while adding all or part of it. The particle size of the acrylic elastomer (A) latex has a large effect on the impact strength of the polyalkylene terephthalate resin composition. If it is too small, it is unfavorable for impact strength, and it is preferable to make it as large as possible without impairing the stability of the latex. The particle size of acrylic elastic material (A) latex is 0.15~
A range of 0.35μ is preferable, and if a rubber with a relatively small particle size is used, the particle size can be adjusted to a suitable size using an enlarging agent such as an acid or an inorganic salt before or during graft polymerization. The graft copolymer (B) was prepared in the presence of 100 parts by weight (as solid content) of the acrylic elastomer (A) latex.
Obtained by graft polymerization of ~125 parts by weight of monomer or monomer mixture. If the amount of the monomer or monomer mixture to be graft-polymerized exceeds 125 parts by weight, the effect of improving impact strength will be small when blended with the polyalkylene terephthalate resin. If the amount of the monomer or monomer mixture to be graft-polymerized is less than 25 parts by weight, it will not only be difficult to operate the graft copolymer in the coagulation and drying process, but also make it difficult to mold the polyalkylene terephthalate resin composition. Workability is extremely poor and impact strength is also low. As monomers to be grafted, methacrylic acid alkyl esters, aromatic vinyl compounds, vinyl cyan compounds, etc. can be used, and each can be graft-polymerized in one stage or in multiple stages, either alone or in combination. Methacrylic acid alkyl esters have an alkyl group having 1 to 4 carbon atoms, and include methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate, and tert-butyl methacrylate. etc. can be used. As the aromatic vinyl compound, in addition to styrene, α-substituted styrene, nuclear-substituted styrene, and derivatives thereof, such as vinyltoluene, α-methylstyrene, chlorostyrene, etc. are used. As the vinyl cyanide compound, acrylonitrile, methacrylonitrile, etc. are used. The amount of the methacrylic acid alkyl ester used can be 100 to 60% by weight based on the total amount of the graft portion. If the amount used is less than 60%, the dispersion state of the graft copolymer in the polyalkylene terephthalate resin will deteriorate, resulting in a decrease in impact resistance and deterioration in surface gloss. An aromatic vinyl compound can also be used to improve fluidity, but the amount used is 0 to 40% by weight based on the total amount of the grafted portion. If the amount used exceeds 40% by weight, the impact resistance improvement effect of the polyalkylene terephthalate resin will be small. The vinyl cyanide compound can be used in an amount of 20 to 0% by weight based on the total amount of the graft portion. If the vinyl cyanide compound is used in an amount of 20% by weight or less, the processability of the polyalkylene terephthalate resin composition will be improved, but if the vinyl cyanide compound is used in an amount of 20% by weight or less,
If it is used in excess of this amount by weight, it may cause coloring or even deteriorate molding processability. As the graft polymerization initiator, the same initiator as used in polymerizing the acrylic elastomer (A) can be used. Graft polymerization is carried out following the production of the acrylic elastomer (A) latex, or by adding an initiator, polymerization regulator, crosslinking agent, etc. as necessary under normal emulsion polymerization conditions in a separate reactor. can be done. In addition, graft polymerization can be carried out by adding the entire amount of each monomer at once, either continuously or discontinuously. The obtained graft copolymer latex is usually subjected to salting out or acid precipitation coagulation, washing with water and drying to recover the graft copolymer in powder form. The resin composition of the present invention consists of 3 to 45 parts by weight of the graft copolymer (B) thus obtained and 97 to 55 parts by weight of the polyalkylene terephthalate resin. If the amount of the graft copolymer is less than 3 parts by weight, the effect of improving impact resistance will be small; if it exceeds 45 parts by weight, the excellent heat resistance and mechanical properties of the polyalkylene terephthalate resin will be impaired, which is not preferable. More than 80 mol% of the polyalkylene terephthalate resin, which is a constituent component of the present invention, has 2 carbon atoms.
A polyester consisting of a homopolymer, a copolymer, or a mixture of these polymers obtained by condensing terephthalic acid or an alkyl ester thereof with 80 mol% or more of the alkylene glycol of 1 to 8. As a copolymer, it may contain other dicarboxylic acids in an amount of less than 20 mol%. Acids, such as isophthalic acid or halogenated terephthalic acid, or poly(alkylene glycols)
etc. are co-condensed together. Preferred polyalkylene terephthalate resins are polyethylene terephthalate and polytetramethylene terephthalate. The resin composition of the present invention may further contain a reinforcing filler in an amount of 2 to 50% by weight based on the total resin composition for the purpose of reinforcing the resin composition. As the reinforcing filler, various types and shapes can be used. For example, fibrous, plate-like (flake-like), spherical, granular, etc. shapes are used.
Specifically, glass fiber, carbon fiber, metal fiber, asbestos, potassium titanate, whiskers, ceramic fiber, milled fiber, glass powder, glass beads, glass foil (flake),
Talc, clay, kaolin, calcium carbonate, calcium metasilicate, processed mineral fiber, dawsonite, silica powder, quartz powder, mica, metal powder,
Examples include titanium oxide, litobone, carbon black graphite, boron nitride, antimony trioxide, sodium antimonate, and one or more of these may be used. Fibrous fillers have a large effect on improving mechanical properties, and flake, spherical, plate-like, and granular fillers have an effect on improving rigidity and heat resistance.
When these and a fibrous filler are used together, the warpage of the molded product can be reduced more than when the fibrous filler is used alone. If the amount of the reinforcing filler added is less than 2% by weight, the reinforcing effect will be insufficient, and if it exceeds 50% by weight, the appearance of the molded product will deteriorate, reducing its commercial value. The reinforcing filler used in the present invention is preferably one that has been subjected to an appropriate surface treatment,
A commonly known silane coupling agent,
Commercially available fillers such as surface-treated fillers such as titanate coupling agents and fillers treated with fatty acids can be used as they are or after surface treatment. The composition of the present invention may optionally contain stabilizers against light or heat such as ultraviolet absorbers and antioxidants, known modifiers such as epoxy resins and fatty acid ester waxes, mold release agents, fluidity improvers, and bromine. Additives such as flame retardants such as chemically modified epoxy and dyes and pigments can be added. The present invention will be explained below with reference to Examples. In addition, "parts" and "%" in the following examples are "parts by weight", respectively.
Means "% by weight". Example 1 (A) Production of acrylic elastomer latex 180 parts of ion-exchanged water substituted with nitrogen was placed in a reaction vessel, and 0.45 parts of boric acid and 0.045 parts of anhydrous sodium carbonate were added.
n-butyl acrylate by dissolving 2.0 parts of potassium oleate and 0.15 parts of potassium persulfate and keeping at 70℃.
49.75 parts, 1,3 butylene dimethacrylate 0.25
of the mixture was added dropwise over a period of 3 hours. After the dropwise addition was completed, the temperature was kept at the same temperature for 1 hour to complete the polymerization. The polymerization rate was 99%, and the resulting latex had an average particle diameter of 0.18 μm and a pH of 7.5. A mixture consisting of 49 parts of n-butyl acrylate and 1 part of allyl methacrylate was added dropwise to this latex over a period of 2 hours while maintaining the temperature at 70 DEG C. After the addition was completed, the mixture was maintained for 1 hour to complete the polymerization. The polymerization rate was 99.5%, the average particle diameter of the acrylic elastic body obtained was 0.22μ, and the pH of the system was 7.1. Table 1 shows Example 1 in which the type and amount of the crosslinking agent and grafting agent in the first and second stages were changed.
-(1) to 1-(9) show cases in which an acrylic elastic body was polymerized in one step as a comparative example. (B) Production of graft copolymer 100 parts of each acrylic elastomer latex obtained in (A) above (as polymer solid content), 100 parts of ion-exchanged water, 0.2 part of sodium formaldehyde sulfoxylate, and potassium oleate. Prepare 0.5 parts,
Keep at 70℃ 30 parts methyl methacrylate, styrene
The mixture was added dropwise over 90 minutes to a mixture of 10 parts of t-butyl hydroperoxide and 0.15 parts of t-butyl hydroperoxide, and after the completion of the addition, the temperature was kept at the same temperature for 1 hour to complete the polymerization. Next, a mixture of 20 parts of methyl methacrylate and 0.07 parts of t-butyl hydroperoxide was added dropwise over 1 hour to advance polymerization, and after completion of the addition, the same temperature was maintained for 1 hour to complete the polymerization. The polymerization rate was 99% or higher, and the resulting graft copolymer had a particle size of 0.27μ. This graph latex was added to an aqueous sulfuric acid solution for acid precipitation coagulation, and then washed, dehydrated, dried, and recovered as a powder. (C) Manufacturing method of polyalkylene terephthalate resin composition Polybutylene terephthalate resin and the graft copolymer obtained in the above (B) are mixed in a ratio of 80/20 (weight ratio).
The mixture was mixed in the following proportions, melt-kneaded using a 40 mmφ vented extruder, and pelletized. The pellets were dried in vacuum and then injection molded. The mechanical properties, including impact resistance, of the resulting molded product are shown in Table 1. In addition, the mechanical properties and Izod impact strength are ASTM-D-256.
-56, manual tensile strength is ASTM-D638, flexural modulus is
Measured according to the ASTM-D790-61 standard. The above results are shown in Table 1.

【table】

[Table] The abbreviations in Table 1 are as follows. Note that the abbreviations are common to the following examples and comparative examples. BA: n-butyl acrylate 1.3BD: 1.3 butylene dimethacrylate AMA: allyl methacrylate DVB: divinylbenzene TAIC: triallyl isocyanurate Example 2 Graft copolymer obtained by Example 1-(1) to 1-(3) The mixture, polybutylene terephthalate, and glass fiber were mixed in a ratio of 20/80/40 (weight ratio), and the same procedure as in Example 1 (C) was carried out to obtain a molded product. The mechanical properties of this molded article are shown in Table 2. A comparative example shows a case where a graft copolymer obtained by polymerizing an acrylic elastic material in one step, a polybutylene terephthalate resin, and glass fiber were mixed in a ratio of 20/80/40.

[Table] Example 3 In the production of the acrylic elastic body in (A) of Example 1-(1), the percentage amounts of the crosslinking agent and grafting agent used in the first and second stages were not changed, and 1 DVB is used as the cross-linking agent in the first stage, and triallyl cyanurate is used as the graft cross-linking agent in the second stage, and the ratio of the amount of monomers in the first stage to the amount of monomers in the second stage is changed as shown in Table 3. Table 3 shows the mechanical properties of a molded article of a polybutylene terephthalate resin composition obtained by carrying out graft polymerization in the same manner as in Example 1 and finally in the same manner as in Example 1 (C).

[Table] Example 4 2-acrylic acid instead of n-butyl acrylate
An acrylic elastic latex was obtained in the same manner as in Example 1 (A) except for using ethylhexyl. 100 parts of this acrylic elastic material (as solid content)
Five types of graft copolymers were obtained by changing the amount of the monomer mixture to be graft-polymerized. However, as an additional emulsifier, 1% of potassium oleate was used based on the monomer mixture to be graft-polymerized. 0.3% each of sodium formaldehyde sulfoxylate and cumene hydroperoxide as polymerization catalysts to the monomer mixture for graft polymerization;
0.35% was used. The ratio of each monomer in the graft polymerized monomer mixture was 80% methyl methacrylate;
15% styrene and 5% acrylonitrile. These graft copolymers and polyethylene terephthalate resin are mixed at a ratio of 20/80 (weight ratio),
Table 4 shows the mechanical properties of the polyethylene terephthalate resin composition molded product obtained in the same manner as in Example 1 (C).

[Table] ○: Good
×: Bad Example 5 The resin composition of Example 1-(1) of the present invention and the commercially available methyl methacrylate-butadiene-styrene resin ( Table 5 shows the weather resistance of resin compositions using MBS resin) and acrylonitrile-butadiene-styrene resin (ABS resin). Weather resistance is measured using a weatherometer (WE-type manufactured by Toyo Rika)
The Izot impact strength and degree of coloration after accelerated exposure treatment are shown.

[Table] *) Appearance change ○: No change in appearance occurred.
×: Appearance change occurs.

Claims (1)

[Scope of Claims] 1. Using an acrylic acid alkyl ester having an alkyl group having 2 to 10 carbon atoms, the first step consists of 99.9 to 97% by weight of the acrylic acid alkyl ester and 0.1 to 3% by weight of a crosslinking agent. 30 to 70 parts by weight of the mixture is subjected to emulsion polymerization, and in the second step, a mixture of 70 to 97% by weight of an acrylic acid alkyl ester and 1 to 3% by weight of a polyfunctional grafting agent having one or more allyl groups is prepared. 30 parts by weight are polymerized to form an acrylic elastic body (A), and 100 to 60 parts by weight of alkyl methacrylate are added to 100 parts by weight of this elastic body (A).
A graft copolymer obtained by graft polymerizing 25 to 125 parts by weight of a monomer or monomer mixture consisting of 40 to 0% by weight of an aromatic vinyl compound and 20 to 0% by weight of a vinyl cyanide compound in one or multiple stages. B) 3-45
Parts by weight, polyalkylene terephthalate resin 97
A resin composition with excellent impact resistance, cold resistance, and weather resistance, consisting of ~55 parts by weight. 2. The resin composition according to claim 1, which contains 2 to 50% by weight of reinforcing filler in the total resin composition.